Pravara is recited at certain points in the sacrificial ritual. It is used to assert the individual's pre-collection identity as a member of the Vedic oral traditions. They are required to pronounce the names of their important ancestors who were the founders of their family. This is usually done when performing sacred acts, repeating prayers, or invoking the Gods. The Pravara chant is specific to their Gotra and is used to invoke the God of Fire, who is believed to carry oblations and prayers to preceptors and the Gods. The recitation of the Pravara forms an integral part of virtually every  Srauta offering , and it is recited by the  Hotr , a member of the Vedic oral traditions agency, in the regular isti. Each Gotra, which is a unit of the Brahmanical exogamous system, is subdivided into several  ganas , each with its own distinctive pravara. All ganas within one Gotra usually have at least one pravara-name in common. While the connection of pravaras with exogamy is considered secondary, the pravara system is closely related to the system of gotras. Gotra refers to a larger exogamous group to which a person belongs. However, as the usage of the term gotra became loosely applied to smaller subdivisions and even individual families, the pravara became necessary to determine the specific exogamous group. The pravara serves as a test to decide to which of the larger exogamous groups a person belongs. [ 2 ] [ 3 ] [ 5 ] [ 8 ]


The recitation of the family pedigree is an important part of the daily  Sandhya ceremonial . It is a religious obligation for every high caste man to preserve the memory of his ancestors and maintain the line of his family descent unbroken. The worshipper declares his gotra and recites the names of his three ancestors (Pravara index) as part of this recitation. [ 8 ]


For instance, a worshipper says:


I belong to a particular gotra (or tribe of Brahmans); I have three ancestors—Angirasa, Sainya, and Gargya; I am a student of the Asvalayana Sutra, and follow the Sakala-Sakha of the Rgveda."' [ 8 ]


Pravara names were recited by Brahmins three times a day in the past, but currently, only a few Brahmins continue this practice. [ 4 ]


The Pravara index is a patrilineal descent formula used to identify one's Gotra lineage in the Vedic tradition. It consists of a list of lineages expressed as a patrilineal descent formula, ranging from a one rishi formula (rare) to a five rishi formula (also rare), but most falling in between, with three rishi formula being the most common. The Pravara formula typically consists of three names, with the first name being the remote ancestor, the second name being an intermediate figure after the remote ancestor, and the third name being the one nearest to the worshipper. [ 9 ] [ 3 ]


An example of a Pravara formula is the  Kaśyapa-Avatsra-Nidhruva  formula, which implies that Kaśyapa is the remote First Singer of the family, Avatsra is an intermediate figure after Kaśyapa, and Nidhruva is the one nearest to the worshipper, the last one, putatively historical and actually so in some instances. [ 9 ]


House laws  ( German :  Hausgesetze ) are rules that govern a  royal family  or  dynasty  in matters of eligibility for  succession to a throne , membership in a dynasty, exercise of a  regency , or entitlement to dynastic  rank ,  titles  and  styles . Prevalent in  European monarchies  during the nineteenth century, few countries have house laws any longer, so that they are, as a category of law, of more historical than current significance. If applied today, house laws are mostly upheld by members of royal and princely families as a matter of  tradition .


Some dynasties have  codified  house laws, which then form a distinct section of the laws of the  realm , e.g.,  Monaco ,  Japan ,  Liechtenstein  and, formerly, most of Germany's principalities, as well as  Austria  and  Russia . Other monarchies had few laws regulating royal life. In still others, whatever laws existed were not gathered in any particular section of the nation's laws. In Germany where many dynasties reigned as more or less independent sovereigns, laws governing dynastic rights constituted a distinct branch of  jurisprudence  called private princely law ( Privatfürstenrecht ).


The house laws of the German ruling families had a direct influence on Scandinavian kingdoms including Denmark and Sweden. [ 1 ]


In some cases, house laws are rules or traditions that are treated as if they have the force of law. In the United Kingdom an example of this might be considered the custom whereby a wife shares in her husband's hereditary titles and rank. While this is settled  common law  with respect to the wives of  peers  and commoners, it is less clear when it comes to consorts of the king and princes. When, in 1923,  Prince Albert, Duke of York  became the first male member of the British royal family to marry a non-princess in more than 300 years (with the sovereign's approval), so an announcement was apparently issued by  Buckingham Palace  and carried in the  London Gazette  and  The Times , "It is officially announced that, in accordance with the settled general rule that a wife takes the status of her husband,  Lady Elizabeth Bowes-Lyon  on her marriage has become Her Royal Highness the Duchess of York, with the status of a Princess".


This issue was re-visited by the British government in 1937 and 2005, when the marriages of a former and a future king to divorcées cast into doubt what titulature was appropriate for women who were to become, essentially, the  private  wives of royal princes . As can be gleaned from discussions at the time, popular certainty that "a woman is entitled to share her husband's status", has by no means been seen as absolutely clear by government experts and lawyers upon examining the matter.


In the case of the marriage of  Prince Charles  to  Camilla Parker Bowles , in 2005, the matter was settled by the decision that Camilla, whilst legally the Princess of Wales, would only use her secondary title of Duchess of Cornwall, out of respect to public sensibilities and to her predecessor,  Diana, Princess of Wales .


Where they have existed, dynastic house laws have often been extraordinary compared to other national laws. The house laws of the families of the Austrian and German emperors were not made public until after the fall of the monarchy in 1918. Luxembourg's grand duke has made modifications to his country's dynastic law that remain unknown to the public at present. Russia's house laws were applied—or not—at the tsar's discretion. Even today, the house laws of the dynasty that has exclusive right to succeed to the throne of  Liechtenstein  may not be amended by either the  parliament  or  populace  of the principality, and until the late 1990s the reigning Prince could not be dethroned except according to the house law—which stipulated that ouster was only possible by a vote of his own family members.


Nearly all house laws have regulated dynasts' right to marry.  Paul I of Russia  established the house law of the  Romanovs  (the  Pauline Laws ), one of the strictest in Europe. The  consorts  of Russian dynasts had to be "equally born" (i.e., belong to a royal or ruling house) and be approved by the tsar.


While some German dynasties included in their laws language requiring or urging the monarch to consent to any "equal" marriage, some heads of dynastic houses rejected royal matches on behalf of their family members. The French pretender denied his daughter,  Princess Hélène d'Orléans , the opportunity to become Queen Consort of Britain by refusing her permission to convert to  Anglicanism  to marry  Prince Albert Victor, Duke of Clarence . In the late 19th or early 20th centuries the monarchs of Belgium, Russia, and Spain all withheld consent from members of their families to marry for love into foreign dynasties:  Grand Duke Cyril Vladimirovich of Russia  and  Infante Alfonso de Borbon-Orléans of Spain  sought to marry a pair of sisters who were also British princesses,  Princess Victoria Melita of Edinburgh  and  Princess Beatrice of Edinburgh , choosing to  elope  and endure (temporary)  banishment  rather than obey their sovereigns' commands.


European dynasties dethroned at the end of World War I continue to enforce their house laws even though they had no legal authority to do so. Some continued doing so through the 20th century ( Bourbon-Sicily ,  Prussia ,  Württemberg ). Governments in extant monarchies, without calling the legal mechanisms  house laws , have generally strengthened their control over the marriages of members of their royal families since the second half of the 20th century. Previously a prince could often  morganatically  marry a woman not deemed acceptable as a royal consort, relegating her and their children to a sub-royal status. That is rarely an option anymore. In most  Western European  monarchies of today, a prince must renounce or  forfeit  membership in the royal house if his chosen spouse is not deemed suitable, e.g.,  Prince Friso of Orange-Nassau .


Hyperdescent  is the practice of classifying a child of mixed  race  ancestry in the more socially dominant of the  parents ' races.


Hyperdescent is the opposite of  hypodescent  (the practice of classifying a child of mixed race ancestry in the more socially subordinate parental race). Both hyperdescent and hypodescent vary from, and may not be mutually exclusive with, other methods of determining lineage, such as  patrilineality  and  matrilineality .


Until well into the 20th century, Australian state and federal governments engaged in a program of forcibly separating Aboriginal children with white ancestry from their  Aboriginal  families, and raising them in institutions that were intended to prepare them for  white  foster homes, jobs under white employers and/or marriage to whites.


This occurred according to theories of hyperdescent that were popular among white people. These ideas were not usually shared by Aboriginal people.  White politicians and officials utilised  pseudo-scientific  theories that Aboriginal people were genetically and culturally inferior to whites, and were becoming extinct. These authorities believed that it was therefore improper for part-white children to live as Aboriginal people.


It was also widely believed that if Aboriginal people whose descendants had children with whites for several generations, successive generations of descendants would be less and less  distinguishable from whites.


In Australia, while there were many racist laws intended to keep Aboriginal people in a socially inferior position, there were no anti- miscegenation  laws and hence no barriers to marriages between Aboriginal and white partners. [ 1 ] [ 2 ] [ clarification needed ]


Brazil  is an example of a country with a history of European  slavery  of black Africans somewhat analogous to that of the  United States of America . However, in the United States, hypodescent was applied, gradually classifying anyone with  African American  ancestry as black, specifically in  one-drop rule  laws passed in Virginia and other states in the 20th century. In Brazil, by contrast, people of mixed race who were fair-skinned or were educated and of higher economic classes were accepted into the elite. Thomas E. Skidmore, in  Black into White: Race and Nationality in Brazilian Thought  explains that many of the Brazilian elite encouraged a national process of " whitening " through  miscegenation . Skidmore writes (p. 55):


In fact, miscegenation did not arouse the instinctive opposition of the white elite in Brazil. On the contrary, it was a well-recognized (and tacitly condoned) process by which a few mixed bloods (almost invariably light  mulattoes ) had risen to the top of the social and political hierarchy.


Hyperdescent is the rule in the rest of  Latin America  as well. The  mestizo  populations of Latin America usually consider themselves to be of European culture rather than  American Indian . This is also apparent in the  United States , where the practice of hypodescent is the rule among the non-Hispanic population contrasting with hyperdescent among  Hispanics . Nearly half of U.S. Hispanics called themselves "white" in the 2000 Census, along with 80% of the population of Puerto Rico. Non-Hispanics, on the other hand, if they are of mixed race, will usually call themselves white only if they are a small fraction (1/8 or 1/16) American Indian, but otherwise will claim being of mixed race or even of the minority race. In the 2000 Census, of 35,305,818 Hispanics, only 407,073 (or just over 1%) called themselves American Indian, and only 2,224,082 (just over 6%) claimed to be of mixed race, even though these Hispanic groups (such as Mexicans) are majority mestizo in their home countries. [ 3 ]


About 41.2% of U.S. Hispanics identify as "Some other race" as of 2006, but government agencies which do not recognize "Some other race" (such as the  FBI , the  CDC , and the  NCHS ) include this group, and therefore over 90% of Hispanics, within the white population. In such cases, such as with the NCHS, separate statistics are often kept for "White" (which includes whites and over 90% of Hispanics) and "non-Hispanic white".


Another example of hyperdescent is in  Iceland , which was initially populated by  Norsemen , who took with them slaves from  Ireland ,  Scotland  and  England , including some women.


Modern  Icelanders  are considered to be a  Scandinavian  people ethnically, although many of the founding generations were Irish, Scottish, or English women.


In societies that regard some  races  or  ethnic groups  of people as dominant or superior and others as subordinate or inferior,  hypodescent  refers to the automatic assignment of children of a mixed union to the subordinate group. [ 1 ]  The opposite practice is  hyperdescent , in which children are assigned to the race that is considered dominant or superior.


Parallel practices include  patrilineality ,  matrilineality , and  cognatic descent , which assign race, ethnicity, or religion according to the father, mother, or some combination, without regard to the race of the other parent. These systems determine group membership based on the gender of the parent rather than the social dominance of the group, and thus can be hypodescent or hyperdescent depending on the genders of the parents and the views of the culture in which they live (i.e.  patriarchal  vs  matriarchal  societies).


Attempts to limit (or eliminate) mixed-race populations by legal means are defined in  anti-miscegenation laws , such as passed by various states in the United States.


While customs, practices and systems of belief emphasizing the value of purity of descent are arguably as old as mankind, few societies systematically codified them, or legally enforced their outcome. Practices were enforced in communities. Such was the case in classical Greece – which made clear distinctions between Greeks and Barbarians. The Roman Republic had a different pattern. While it was expansionist, and militarily and culturally aggressive, it actively encouraged the Romanisation of client kingdoms, which included intermarriage of Romans with their elite citizens and making this class citizens of Rome as reward and as exemplars.


The North American practice of applying a rule of hypodescent began during the colonial era when indentured servants and transported convicts working at the direction of European colonists and colonial authorities were joined by enslaved Africans that from the 16th century onwards were transported to the Americas via the  Atlantic slave trade . But while the freed captives were Christians, these individuals were classified as indentured workers. [ citation needed ]


Virginia formally enacted a  slave code  in 1705. There is documentary evidence from the 1650s that some Africans in Virginia were serving lifelong terms of indenture. In the 1660s, the Assembly stated that "any English servant that shall run away in company with any Negroes who are incapable of making satisfaction by addition of time shall serve for the time of the said Negroes absence", indicating that at least some Africans could not "make satisfaction" by serving longer if recaptured (presumably because they were already indentured for life). This device gave legal status to the practice of lifetime enslavement of people of African descent; in subsequent statutes the legislature defined conditions of lifetime servitude.


In 1655,  Elizabeth Key Grinstead , a  mixed-race  woman, fought and won the first  freedom suit  in Virginia. Her English father had acknowledged her as his daughter, had her baptized as Christian, and, falling ill, established a legal guardian to care for her after his death, arranging a limited-term indenture for her as a girl. But the guardian sold her indenture and left the colony, and the next master did not free her. When he died, his estate claimed her and her son as slave property. [ 2 ]


However, following Key's victory, Virginia established the principle in law in 1662 of  partus sequitur ventrem , from  Roman law ; that is, children born in the colonies would take the social status of their mothers. This meant that all children born to enslaved women would be born into slavery, regardless of their paternity and race. This was in contrast to English common law, by which the status of children of English subjects was determined by the father. [ 2 ]


As slavery became a racial caste system, people of only partial African ancestry and majority European ancestry were born into slavery. African descent became associated with slavery. By hypodescent, people of even partial African ancestry were classified socially below whites. By the late 18th century, there were numerous families of majority-white slaves, such as the mixed-race children born to the slave  Sally Hemings  and her master  Thomas Jefferson . She was three-quarters white and the half-sister of his late wife; their children, born into slavery, were seven-eighths white. Jefferson gave the four surviving children their freedom as adults; [ citation needed ]  three assimilated into white society. [ citation needed ]


The Southern author  Mary Chesnut  wrote in her famous  A Diary from Dixie , of the  Civil War -era, that "any lady is ready to tell you who is the father of all mulatto children in everybody’s household but her own. Those, she seems to think, drop from the clouds." [ 3 ]


Fanny Kemble , the British actress who married an American slaveholder, wrote about her observations of slavery as well, including the way white men sexually abused slave women and left their mixed-race children enslaved.


Sometimes the white fathers freed the children and/or their mothers, or provided education or apprenticeship, or settled property on them in a significant transfer of social capital. Notable  antebellum period  examples of fathers who provided for their mixed-race children were the fathers of  Charles Henry Langston  and  John Mercer Langston  and the father of the  Healy family of Georgia . Each had a common-law marriage with a woman of partial African descent. Other mixed-race children were left enslaved; some were sold away by their fathers. [ 4 ]


Research by historians and  genealogists  has shown that unlike the above examples, most free African Americans listed in the first two US censuses in the Upper South were descended from relationships or marriages in colonial Virginia between white women, indentured servant or free, and African or African-American men, indentured servant, free or slave. Their unions reflected the fluid nature of relationships among the working classes before slave caste was hardened, as well as the small households and farms within which many people worked. The children of white mothers were born free. If they were illegitimate and mixed race, they were apprenticed in order to avoid the community being burdened with upkeep, but such people gained a step in freedom. [ 5 ]


By the turn of the nineteenth century, many of these families of free African Americans, along with European-American neighbors, migrated to frontier areas of Virginia, North Carolina, and then further west. Such families sometimes settled in insular groups. Mixed-race people of African-European descent are believed to have been the origin of some isolated settlements, which have long claimed or were said to be of  American Indian  or  Portuguese  ancestry. [ 5 ]  As an example, a 21st-century  DNA  study of a group of  Melungeon  families in Tennessee and Kentucky, long rumored to be descendants of Turks or Native Americans, showed they were overwhelmingly of African and European ancestry.


By the late 1870s, conservative white Democrats regained power in state legislatures across the South, even in areas where there were black majorities, largely by a process of violence and intimidation of black Republicans. The Democrats gradually imposed  white supremacy  in law and practice. From 1890 to 1908, beginning with Mississippi, the state legislatures passed new constitutions and laws that created barriers to voter registration by such means as the  poll tax ,  literacy tests , record requirements and others. The number of voters on the rolls fell drastically and most blacks and many poor whites were  disenfranchised  for decades. The whites also passed  Jim Crow laws , such as  racial segregation  of public facilities.


African Americans and whites established the  National Association for the Advancement of Colored People  in 1909 to fight against legal discrimination and disenfranchisement. Each time they won a court case, for instance, against the use of  white primaries , white-dominated legislatures would pass new laws to exclude blacks from the political system.


In the 20th century, under influences of  eugenics  and racial discrimination, states enacted laws classifying people as black who had any traceable evidence (or perception of any African ancestry). Under Virginia's  Racial Integrity Act  of 1924, the  'One-drop' rule  defined as black a person with  any  known African ancestry, regardless of the number of intervening generations.


The same Act established a binary classification system for vital records, classifying people as 'white' or 'black' (Negro at the time). The latter was effectively a 'catch all' term for all people of color. Native Americans were classified as colored, a clear indication of the then-prevalent local attitude to  all  races other than white.


In its most extreme form in the United States, hypodescent was the basis of the " one drop rule ", meaning that if an individual had any black ancestry, the person was classified as black. Laws were passed in southern states and others in the early 20th century, long after the end of slavery to define white and black, under associated laws for segregation:  Tennessee  adopted such a "one-drop" statute in 1910;  Louisiana ;  Texas ;  Arkansas  in 1911;  Mississippi  in 1917;  North Carolina  in 1923;  Virginia  in 1924;  Alabama  and  Georgia  in 1927; and  Oklahoma  in 1931.


During this same period,  Florida ,  Indiana ,  Kentucky ,  Maryland ,  Missouri ,  Nebraska ,  North Dakota , and  Utah  retained their old "blood fraction" statutes  de jure , but amended these fractions (one-sixteenth, one-thirtysecond) to be equivalent to one-drop  de facto . [ 6 ]


By 1924 many "white" people in Virginia would have had some African and/or Native American ancestry, given the mixing over the centuries. At the same time that Virginia was trying to harden racial caste, African Americans were organizing to overturn segregation and regain civil rights, that had been lost to  Jim Crow  laws and  disfranchisement  of the majority of the black community.


By the early 1940s, of the thirty  U.S. states that had  anti-miscegenation laws , seven states ( Alabama ,  Arizona ,  Georgia ,  Montana ,  Oklahoma ,  Texas , and  Virginia ) had adopted the  one-drop theory  for rules prohibiting  interracial marriages . [ 7 ]  This was part of a continuing social hardening of racial lines after the turn of the century, when southern states imposed legal segregation and disfranchised African Americans.


Other states applied the hypodescent rule without carrying it to the "one-drop" extreme, using instead a  blood quantum  standard.  For example,  Utah 's anti- miscegenation  law prohibited marriage between a white and anyone considered a  negro ,  mulatto ,  quadroon  (one-fourth black),  octoroon  (one-eighth black),  Mongolian , or member of "the  Malay race " (here referring to  Filipinos ).  No restrictions were placed on marriages between people who were not "white people". The law was repealed in 1963.


In the  United States , hypodescent has often defined children of mixed-race couples as black when one parent is classified as "black", or either is thought to have African descent.


Since the 1960s particularly and the rise of the  Black Power  movement, many members of the African-American community have emphasized that mixed-race individuals of African descent should identify as black in order to maximize their political power as a group in the United States. Leaders say they were historically discriminated against as black by white people, so should identify as black to assert their power in numbers.


President of the United States  Barack Obama  is often referred to as the first black or African-American President. He has said as a youth that he chose to identify as black and worked in community organizing in a black community. His mother and her parents were of European descent; his father and his family are sub-Saharan African from  Kenya . But, in a case exemplifying the complex racial history of the United States, Obama is believed to be descended through his maternal line from  John Punch , the first African documented historically as a slave in Virginia. [ 8 ]  The genealogical company Ancestry.com sponsored a study of his family history and documented this connection. Punch's descendants increasingly married white and are believed to have been accepted as white by the early 18th century. [ 8 ]


In the history of the US, people have less consistently applied hypodescent in intermarriage between white people and people of other racial groups, such as Native Americans, and Asians. [ citation needed ]  There was certainly discrimination against people of mixed European and Native American, and European and Asian ancestry, however.


Hypodescent is not only practiced by people of European ancestry. In  Omaha, Nebraska , white people have celebrated  Logan Fontenelle , a mixed-race man of the late 19th century who served as interpreter for a major treaty between the  Omaha Nation  and the United States that ceded most of their land before they moved to a reservation. White people referred to Fontenelle as chief of the Omaha, and he was one of the signatories of the treaty along with Omaha chiefs, perhaps because he spoke English. Various places in the city of Omaha were named after Fontenelle. But among the Omaha, Fontenelle was considered a white man because his father was white, and he was never a recognized chief. As the Omaha had a  patrilineal   kinship  society, hereditary chieftainship and descent were passed through the male line. A person whose father was white was not considered Omaha unless he was formally adopted by a male Omaha member. [ 9 ]


Both African-American and white authors have explored issues related to mixed race and hypodescent in fiction and non-fiction.


In the novel  Pudd'nhead Wilson , by  Mark Twain , the character of the enslaved woman Roxy is described as "Negro", although she has considerable white ancestry and could  pass for white . Her son is born into slavery and is 1/32 part black. He is mistakenly switched in infancy with the white son of the master's household, and each grows up to fulfill his social role.


The US late-19th century author  Charles Chesnutt , who grew up free in Ohio and was of mixed African-European ancestry, wrote numerous stories set in the post-Civil War South. He explored the issues encountered by people of mixed race, in some cases relating what became known as the  tragic mulatto  genre.


Passing  is a 1929 novel by  Nella Larsen , dealing with mixed-race African-American women who choose alternate paths for marriage and identity.


In the musical  Show Boat  (1927), a white man is married to a  mixed-race  woman passing for white. He is accused by the sheriff of violating the state's anti-miscegenation laws. The white man pricks his wife's finger with a knife, swallows a drop of blood, then tells the sheriff "I'm no white man – I've got negro blood in me."  The sheriff lets him off.


Sinclair Lewis's  novel  Kingsblood Royal  uses hypodescent and the "one drop" principle as principal plot elements.


Numerous memoirs have been published by African Americans who explore growing up as mixed race with a white parent, such as  The Color of Water: A Black Man's Tribute to His White Mother  by  James McBride .  Bliss Broyard, in  One Drop: My Father's Hidden Life , wrote about her father  Anatole Broyard 's decision to live and work as a writer, rather than a black writer, largely separating from his mixed-race,  Louisiana Creole  family. He married a white woman of Swedish descent and their children appear white.


Ibn Inabah  ( in  Arabic :  اِبْن‌ِ عِنَبه ) with the full name of  Sayyid Jamaluddin Ahmad ibn Ali ibn Hussein ibn Muhanna Hassani Husseini  ( in  Arabic :  سید جمال‌الدین احمد بن علی بن حسین بن مهنا حسنی حسینی ), (born 748  AH , 1347  AD/CE  - died 828  AH , 1425  AD/CE , at the age of 77) was a  Shiite   historian  and  genealogist . He is from the clan of  Alawi   Sayyids  and his genealogy is related to  Hasan ibn Ali  through his father and to  Husayn ibn Ali  through his mother. He was called  Ibn Inabah  ( in  Arabic :  اِبْن‌ِ عِنَبه ) because  "Inabah Asghar"  ( in  Arabic :  عنبه اصغر ) was in his lineage. However, some have mistakenly called him  Ibn Utabah  ( in  Arabic :  ابن عتبه ) and  Ibn Aqabah  ( in  Arabic :  ابن عقبه ). Although his sect has been questioned, some have accepted his  Imamiyyah  status and have only questioned whether he is a  Zaydi  or not. [ 1 ]


His most important work is "Umdat al-Talib fi Ansabi Ale Abi Talib" ( in  Arabic :  عمدة الطالب فی انساب آل ابی طالب ,  lit.   ' The Seeker's Guide to the Genealogies of the Family of Abi Talib ' ) which is written in  Arabic language . In this book,  Ibn Inabah  describes the biography of  Abu Talib ibn Abd al-Muttalib 's ( the leader of  Banu Hashim , a clan of the  Qurayshi  tribe of  Mecca  in the  Hejazi  region of the  Arabian Peninsula , he being the brother of  Abdullah ibn Abd al-Muttalib , the father of the Islamic  Prophet   Muhammad [ 2 ] ) ancestors and then his descendants. Finally, he describes in more detail the descendants of  Ali ibn Abi Talib  ( the cousin and son-in-law of the Islamic prophet  Muhammad , and the first  Shia   Imam ) through his children:  Hasan ibn Ali  ( the second  Shia   Imam ),  Husayn ibn Ali  ( the third  Shia   Imam ),  Muhammad ibn al-Hanafiyya ,  Abbas ibn Ali  ( also known by the  kunya   Abu al-Fadl , in  Arabic :  أَبو الْفَضْل ,  lit.   'The Father of the Virtues', was a son of  Ali ibn Abi Talib ), and  Umar ibn Ali  ( in  Arabic :  عُمَر بن عَلیّ , one of the children of  Ali ibn Abi Talib  who accompanied his brother,  Husayn ibn Ali , to  Karbala  and was killed on the day of  Ashura ) in five chapters. [ 3 ] [ 4 ] [ 5 ] [ 6 ] [ 7 ]


" Sayyid  Ahmad ibn Ali ibn Al-Hussein ibn Ali ibn Muhanna ibn Inabah" known as  Ibn Inabah  was born in 748  AH  - 1347  AD/CE .  Ibn Inabah  passed away in the city of  Kerman  in  Iran  in the month of  Safar  828  AH  - January 1425  AD/CE  at the age of 77. [ 8 ]


Ibn Inabah  was probably born in  Hillah ,  Iraq . According to his autobiography, his lineage reaches back to  Ali ibn Abi Talib  ( the first  Shia   Imam ) through 20 intermediaries. He is considered a descendant of  Abd Allah al-Mahd  ( an  Islamic scholar ,  theologian  and  hadith  narrator, grandson of both  Hasan ibn Ali  and  Husayn ibn Ali ), hence his lineage is " Hassani - Husseini ". His relationship is to  Hasan ibn Ali  ( the second  Shia   Imam ) through his father and to  Husayn ibn Ali  ( the third  Shia   Imam ) through his mother, and this is why  Ibn Inabah  is sometimes called " Hassani " [ 9 ]  and sometimes " Husseini ". [ 10 ]  He is also called " Dawoodi " because " Muhammad ibn Dawood ibn Mousa al-Thani " was one of his ancestors. [ 11 ] [ 12 ]


His fame as  Ibn Inabah  ( in  Arabic :  اِبْن‌ِ عِنَبه ) is due to the fact that his grandfather was called " Inabah Asghar " ( in  Arabic :  عنبه اصغر ), who in turn was a descendant of " Inabat ibn Muhammad Wared (Inabah Akbar) " ( in  Arabic :  عنبة بن محمد وارد (عنبه اکبر) ). [ 13 ]  "Inabah Akbar" ( in  Arabic :  عنبه اکبر ) was the ancestor of a tribe of " Bani al-Hassan " ( children and grandchildren of  Hasan ibn Ali , the second  Shia   Imam ) nobles who lived in  Iraq , around  Hillah  city. [ 14 ]


From his early youth,  Ibn Inabah  studied genealogy under the supervision of " Abu Abdullah Muhammad ibn Qasim ibn Mu'ayyah Dibaji " ( in  Arabic :  ابوعبدالله محمد بن قاسم بن معیه دیباجی , died 776  AH  - 1374  AD/CE ) known as " Ibn Mu'ayyah " ( in  Arabic :  ابن مُعَيَّه ).  Ibn Inabah  became the beloved and the noble of his master " Ibn Mu'ayyah " among colleagues. During his education,  Ibn Inabah  benefited from numerous sources and teachers, but he undoubtedly gained the most scientific knowledge from the works of his bold master " Ibn Mu'ayyah ". [ 15 ]  As can be seen from  Ibn Inabah  circumstances, after the death of his master " Ibn Mu'ayyah ", he embarked on a journey of exploration and traveled to  Isfahan ,  Herat ,  Samarkand ,  Mecca , and Mazaar (in the Mishan Plain), and benefited from the knowledge of many genealogists. [ 16 ]


Ibn Inabah  can be considered to be on the same level with  Muhammad ibn Makki  ( known as "First Martyr", in  Arabic :  الشهيد الأول , a famous  jurist  who sacrificed his life for his religion ). Both of these individuals were engaged in narrating and transmitting  hadiths  through " Ibn Mu'ayyah " from  al-Allama al-Hilli  ( one of the most influential  Twelver Shi'i Muslim  authors of all time ). [ 17 ]


Ibn Inabah' s sect is not very clear in the history, and several opinions have been expressed on this matter. Some have doubted whether he is a  Shiite . [ 18 ]  But this seems to be incorrect, although it is not certain that he was a  Twelver   Shia . [ 19 ]


Some have considered  Ibn Inabah  a  Zaydi  ( one of the three main branches [ 20 ]  of  Shia Islam ), [ 19 ]  because his expressions and his references confirm that he was a member of  Zaydism  sect. For example,  Ibn Inabah  says about  Muhammad al-Mahdi  ( known as  Mahdi  in  Shia   Islam , the last of the  Twelve Imams  in  Shia , it is believed that The Lord has given him a very long divine life and that he is living secretly among people until the moment his divine mission is revealed, a figure in  Islamic eschatology  who is believed to appear at the  End of Times  to rid the world of evil and injustice ): "There is a twelfth  Imam  according to the  Imamiyyah , and he is the awaited  Mahdi  according to them." [ 21 ]  And more importantly, in the preface to "Umdat al-Talib Timuri" ( the same book "Umdat al-Talib fi Ansabi Ale Abi Talib" by Ibn Inabah which was dedicated to the then emperor,  Timur ), [ 22 ]  where  Ibn Inabah  speaks about the qualities of  Amir   Timur Gurkani , he praises him in the following words: "... the owner of the sublime kingdoms, possessing the prophetic knowledge, the truthful eloquence, the noble verifier with immunity, the luminous generosity, and the approved enthusiasm...". All of these, is evidence that he was a  Zaydi . [ 23 ]


Some have also considered  Ibn Inabah  an  Imami   Shia  and believe that the possibility of him being both a  Shia  and an  Imami  is more acceptable. Especially since  Ibn Inabah  was the student and son-in-law of the  Shiite  scholar, " Ibn Mu'ayyah ", and spent the first part of his life in his service, benefiting from his knowledge, and always remaining loyal to his master. [ 23 ] [ 24 ]


The surviving works or those attributed to  Ibn Inabah  are all in the field of  genealogy  and are of great value and credibility. [ 23 ] [ 24 ]


" Umdat al-Talib fi Ansabi Ale Abi Talib " ( in  Arabic :  عمدة الطالب فی انساب آل ابی طالب ,  lit.   ' The Seeker's Guide to the Genealogies of the Family of  Abi Talib ' ), is the  Ibn Inabah' s most important work. This book is of great importance in the science of genealogy. [ 25 ]   Ibn Inabah  has written this work 3 times in different volumes. The first edition, which is the most detailed but irregular, is known as the "Umdat al-Talib Timuri" ( with the suffix "Timuri" due to its dedication to the emperor of the time,  Timur Gurkani ). The second edition is known as "Umdat al-Talib Jalali" ( with the suffix "Jalali" due to its dedication to the 25th  Nizari Isma'ili   Imam ,  Jalaluddin Hassan ), and the author,  Ibn Inabah , compiled it in 812  AH  - 1409  AD/CE  by selecting about two-thirds of the first edition and adding an introduction. [ 26 ] [ 27 ] [ 28 ]   Ibn Inabah  prepared the third edition for  Sultan   Muhammad ibn Falah Musha'sha'ie  ( an  Iraqi -born  theologian  who founded the  Musha'sha'iya , a  Shia   sect , the living ancestor of  Sadat  and the ruler of "Huwayzah" at the time ) and finished writing it on 10  Safar  827  AH  - 22 January 1424  AD/CE . [ 29 ]


In the preface to the first two editions,  Ibn Inabah  says that he wrote this book because a group of people doubted the genealogy of the family of  Abi Talib . [ 30 ] [ 31 ]  In this book,  Ibn Inabah  describes the biography of  Abu Talib's  ancestors and then his descendants. Finally, he describes in more detail the lineage of  Ali ibn Abi Talib  ( the first  Shia   Imam ) through his children:  Hasan ibn Ali  ( the second  Shia   Imam ),  Husayn ibn Ali  ( the third  Shia   Imam ),  Muhammad ibn al-Hanafiyya ,  Abbas ibn Ali  ( also known by the  kunya   Abu al-Fadl , in  Arabic :  أَبو الْفَضْل ,  lit.   'The Father of the Virtue', was a son of  Ali ibn Abi Talib ), and  Umar ibn Ali  ( in  Arabic :  عُمَر بن عَلیّ , one of the children of  Ali ibn Abi Talib  who accompanied his brother,  Husayn ibn Ali , to  Karbala  and was killed on the day of  Ashura ) in five chapters. [ 23 ] [ 24 ] [ 32 ]


Ibn Inabah' s another book, "Al-Fosul al-Fakhriyah fi Usul al-Bariyah" ( in  Arabic :  الفصول الفخریة فی اصول البریة ,  lit.   ' Honorary Chapters in the Principles of Creation ' ), is in  Persian language  and was published in  Tehran  in 1346  SH  - 1967  AD/CE  with the efforts of " Jalaluddin Hosseini Mohaddes Armavi ". [ 23 ] [ 28 ]  This book briefly describes the lineage from  Adam  to  Noah . [ 33 ]


This book has an introduction and 3 chapters, the title of the introduction is "On the Explanation of the Origin of Generation". In this book, the human lineage from  Adam  to  Noah  is briefly described, then Noah's descendants are followed in greater detail and with clearer classification, and the descendants of each of Noah's descendants are mentioned, especially the kings of  Mesopotamia ,  Iran , and other places. The scope of this genealogy extends to the  Arab  tribes and the ancestors of the Prophet " Muhammad " and is linked to  Abu Talib , and finally the children of Abu Talib are examined and arranged in the style and context of the main author, like the edition "Jalali Umdat al-Talib". In this book,  Ibn Inabah  sometimes criticizes the opinions of others. [ 34 ]


Ibn Inabah  wrote this book for " Fakhruddin Hassan ibn Shamsuddin Muhammad ", who was a famous scholar in  Sabzevar , a descendant of  Imam   Ali al-Sajjad  ( also known as "Zayn al-Abidin", in  Arabic :  زين العابدين ,  lit.   'The Ornament of the Worshippers', was the great-grandson of the  Islamic prophet   Muhammad , and the fourth  imam in Shia Islam ), succeeding his father,  Husayn ibn Ali  ( the third  Shia   Imam ), his uncle,  Hasan ibn Ali  ( the second  Imam  in  Shia ), and his grandfather,  Ali ibn Abi Talib  ( the first  Imam  in  Shia ). [ 35 ]


Other works by  Ibn Inabah , manuscripts of which are available, are as follows: [ 23 ] [ 24 ]


Inbreeding  is the production of  offspring  from the  mating  or breeding of individuals or  organisms  that are closely  related genetically . [ 1 ]  By analogy, the term is used in  human reproduction , but more commonly refers to the genetic disorders and other consequences that may arise from expression of  deleterious   recessive  traits resulting from  incestuous  sexual relationships and  consanguinity . Animals avoid inbreeding only rarely. [ 2 ]


Inbreeding results in  homozygosity  which can increase the chances of offspring being affected by recessive  traits . [ 3 ]  In extreme cases, this usually leads to at least temporarily decreased  biological fitness  of a  population [ 4 ] [ 5 ]  (called  inbreeding depression ), which is its ability to survive and reproduce. An individual who inherits such deleterious traits is colloquially referred to as  inbred . The avoidance of expression of such deleterious recessive  alleles  caused by inbreeding, via  inbreeding avoidance  mechanisms, is the main selective reason for outcrossing. [ 6 ] [ 7 ]  Crossbreeding between populations sometimes has positive effects on fitness-related traits, [ 8 ]  but also sometimes leads to negative effects known as  outbreeding depression . However, increased homozygosity increases the probability of fixing beneficial alleles and also slightly decreases the probability of fixing deleterious alleles in a population. [ 9 ]  Inbreeding can result in purging of deleterious alleles from a population through  purifying selection . [ 10 ] [ 11 ] [ 12 ]


Inbreeding is a technique used in  selective breeding . For example, in  livestock breeding , breeders may use inbreeding when trying to establish a new and desirable  trait  in the stock and for producing distinct families within a breed, but will need to watch for undesirable characteristics in offspring, which can then be eliminated through further selective breeding or  culling . Inbreeding also helps to ascertain the type of gene action affecting a trait. Inbreeding is also used to reveal deleterious recessive alleles, which can then be eliminated through  assortative breeding  or through culling. In  plant breeding ,  inbred lines  are used as stocks for the creation of  hybrid  lines to make use of the effects of  heterosis . Inbreeding in plants also occurs naturally in the form of  self-pollination .


Inbreeding can significantly influence  gene expression  which can prevent inbreeding depression. [ 13 ]


Offspring of biologically related persons are subject to the possible effects of inbreeding, such as  congenital birth defects . The  chances of such disorders  are increased when the biological parents are more closely related. This is because such pairings have a 25% probability of producing  homozygous  zygotes, resulting in offspring with two  recessive alleles , which can  produce disorders  when these alleles are deleterious. [ 14 ]  Because most recessive alleles are rare in populations, it is unlikely that two unrelated partners will both be carriers of the same deleterious allele; however, because close relatives share a large fraction of their alleles, the probability that any such deleterious allele is inherited from the common ancestor through both parents is increased dramatically. For each homozygous recessive individual formed there is an equal chance of producing a homozygous dominant individual — one completely devoid of the harmful allele. Contrary to common belief, inbreeding does not in itself alter allele frequencies, but rather increases the relative proportion of homozygotes to heterozygotes; however, because the increased proportion of deleterious homozygotes exposes the allele to  natural selection , in the long run its frequency decreases more rapidly in inbred populations.  In the short term, incestuous reproduction is expected to increase the number of spontaneous abortions of zygotes, perinatal deaths, and postnatal offspring with birth defects. [ 15 ]  The advantages of inbreeding may be the result of a tendency to preserve the structures of alleles interacting at different loci that have been adapted together by a common selective history. [ 16 ]


Malformations or harmful traits can stay within a population due to a high homozygosity rate, and this will cause a population to become fixed for certain traits, like having too many bones in an area, like the vertebral column of wolves on  Isle Royale  or having cranial abnormalities, such as in  Northern elephant seals , where their cranial bone length in the lower mandibular tooth row has changed. Having a high homozygosity rate is problematic for a population because it will unmask recessive deleterious alleles generated by mutations, reduce heterozygote advantage, and it is detrimental to the survival of small, endangered animal populations. [ 17 ]  When deleterious recessive alleles are unmasked due to the increased homozygosity generated by inbreeding, this can cause inbreeding depression. [ 18 ]


There may also be other deleterious effects besides those caused by recessive diseases. Thus, similar  immune systems  may be more vulnerable to infectious diseases (see  Major histocompatibility complex and sexual selection ). [ 19 ]


Inbreeding history of the population should also be considered when discussing the variation in the severity of inbreeding depression between and within species. With persistent inbreeding, there is evidence that shows that inbreeding depression becomes less severe. This is associated with the unmasking and elimination of severely deleterious recessive alleles. However, inbreeding depression is not a temporary phenomenon because this elimination of deleterious recessive alleles will never be complete.  Eliminating slightly deleterious mutations through inbreeding under moderate selection is not as effective. Fixation of alleles most likely occurs through  Muller's ratchet , when an asexual population's genome accumulates deleterious mutations that are irreversible. [ 20 ]


Despite all its disadvantages, inbreeding can also have a variety of advantages, such as ensuring a child produced from the mating contains, and will pass on, a higher percentage of its mother/father's genetics, reducing the  recombination load , [ 21 ]  and allowing the expression of recessive advantageous phenotypes. Some species with a  Haplodiploidy  mating system depend on the ability to produce sons to mate with as a means of ensuring a mate can be found if no other male is available.  It has been proposed that under circumstances when the advantages of inbreeding outweigh the disadvantages, preferential breeding within small groups could be promoted, potentially leading to  speciation . [ 22 ]


Autosomal recessive  disorders occur in individuals who have  two copies of an allele  for a particular recessive genetic  mutation . [ 23 ]  Except in certain rare circumstances, such as new mutations or  uniparental disomy , both parents of an individual with such a disorder will be carriers of the gene. These carriers do not display any signs of the mutation and may be unaware that they carry the mutated gene. Since relatives share a higher proportion of their genes than do unrelated people, it is more likely that related parents will both be carriers of the same recessive allele, and therefore their children are at a higher risk of inheriting an autosomal recessive genetic disorder. The extent to which the risk increases depends on the degree of genetic relationship between the parents; the risk is greater when the parents are close relatives and lower for relationships between more distant relatives, such as second cousins, though still greater than for the general population. [ 24 ]


Children of parent-child or sibling-sibling unions are at an increased risk compared to cousin-cousin unions. [ 25 ] : 3   Inbreeding may result in a greater than expected phenotypic expression of deleterious  recessive alleles  within a population. [ 26 ]  As a result, first-generation inbred individuals are more likely to show physical and health defects, [ 27 ] [ 28 ]  including:


The isolation of a small population for a period of time can lead to inbreeding within that population, resulting in increased genetic relatedness between breeding individuals. Inbreeding depression can also occur in a large population if individuals tend to mate with their relatives, instead of mating randomly.


Due to higher  prenatal  and  postnatal  mortality rates, some individuals in the first generation of inbreeding will not live on to reproduce. [ 31 ]  Over time, with isolation, such as a  population bottleneck  caused by purposeful ( assortative ) breeding or natural  environmental  factors, the deleterious inherited traits are culled. [ 6 ] [ 7 ] [ 32 ]


Island species are often very inbred, as their isolation from the larger group on a mainland allows natural selection to work on their population. This type of isolation may result in the formation of  race  or even  speciation , as the inbreeding first removes many deleterious genes, and permits the expression of genes that allow a population to adapt to an  ecosystem . As the adaptation becomes more pronounced, the new species or race radiates from its entrance into the new space, or dies out if it cannot adapt and, most importantly, reproduce. [ 33 ]


The reduced  genetic diversity , for example due to a bottleneck will unavoidably increase inbreeding for the entire population. This may mean that a  species  may not be able to adapt to changes in environmental conditions. Each individual will have similar immune systems, as immune systems are genetically based. When a species becomes  endangered , the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in  extinction .


Natural breedings include inbreeding by necessity, and most animals only migrate when necessary. In many cases, the closest available mate is a mother, sister, grandmother, father, brother, or grandfather. In all cases, the environment presents stresses to remove from the population those individuals who cannot survive because of illness. [ citation needed ]


There was an assumption [ by whom? ]  that wild populations do not inbreed; this is not what is observed in some cases in the wild. However, in species such as  horses , animals in  wild  or  feral  conditions often drive off the young of both sexes, thought to be a mechanism by which the species instinctively avoids some of the genetic consequences of inbreeding. [ 34 ]  In general, many mammal species, including humanity's closest  primate  relatives, avoid close inbreeding possibly due to the deleterious effects. [ 25 ] : 6


Although there are several examples of inbred populations of wild animals, the negative consequences of this inbreeding are poorly documented. [ citation needed ]  In the  South American sea lion , there was concern that recent population crashes would reduce genetic diversity. Historical analysis indicated that a population expansion from just two matrilineal lines was responsible for most of the individuals within the population. Even so, the diversity within the lines allowed great variation in the gene pool that may help to protect the South American sea lion from extinction. [ 35 ]


In lions,  prides  are often followed by related males in bachelor groups. When the dominant male is killed or driven off by one of these bachelors, a father may be replaced by his son. There is no mechanism for preventing inbreeding or to ensure outcrossing. In the prides, most lionesses are related to one another. If there is more than one dominant male, the group of  alpha males  are usually related. Two lines are then being "line bred". Also, in some populations, such as the  Crater  lions, it is known that a population bottleneck has occurred. Researchers found far greater genetic  heterozygosity  than expected. [ 36 ]  In fact, predators are known for low genetic variance, along with most of the top portion of the trophic levels of an  ecosystem . [ 37 ]  Additionally, the alpha males of two neighboring prides can be from the same litter; one brother may come to acquire leadership over another's pride, and subsequently mate with his 'nieces' or cousins. However, killing another male's cubs, upon the takeover, allows the new selected gene complement of the incoming alpha male to prevail over the previous male. There are genetic  assays  being scheduled for lions to determine their genetic diversity. The preliminary studies show results inconsistent with the outcrossing paradigm based on individual environments of the studied groups. [ 36 ]


In Central California,  sea otters  were thought to have been driven to extinction due to over hunting, until a small colony was discovered in the Point Sur region in the 1930s. [ 38 ]  Since then, the population has grown and spread along the central Californian coast to around 2,000 individuals, a level that has remained stable for over a decade. Population growth is limited by the fact that all Californian sea otters are descended from the isolated colony, resulting in inbreeding. [ 39 ]


Cheetahs are another example of inbreeding. Thousands of years ago, the cheetah went through a population bottleneck that reduced its population dramatically so the animals that are alive today are all related to one another. A consequence from inbreeding for this species has been high juvenile mortality, low fecundity, and poor breeding success. [ 40 ]


In a study on an island population of song sparrows, individuals that were inbred showed significantly lower survival rates than outbred individuals during a severe winter weather related population crash. These studies show that inbreeding depression and ecological factors have an influence on survival. [ 20 ]


The  Florida panther  population was reduced to about 30 animals, so inbreeding became a problem. Several females were imported from Texas and now the population is better off genetically. [ 41 ] [ 42 ]


A measure of inbreeding of an individual A is the probability  F (A) that both alleles in one locus are derived from the same allele in an ancestor.  These two identical alleles that are both derived from a common ancestor are said to be  identical by descent . This probability F(A) is called the " coefficient of inbreeding ". [ 43 ]


Another useful measure that describes the extent to which two individuals are related (say individuals A and B) is their coancestry coefficient f(A,B), which gives the probability that one randomly selected allele from A and another randomly selected allele from B are identical by descent. [ 44 ]  This is also denoted as the kinship coefficient between A and B. [ 45 ]


A particular case is the self-coancestry of individual A with itself, f(A,A), which is the probability that taking one random allele from A and then, independently and with replacement, another random allele also from A, both are identical by descent. Since they can be identical by descent by sampling the same allele or by sampling both alleles that happen to be identical by descent, we have f(A,A) = 1/2 + F(A)/2. [ 46 ]


Both the inbreeding and the coancestry coefficients can be defined for specific individuals or as average population values. They can be computed from genealogies or estimated from the population size and its breeding properties, but all methods assume no selection and are limited to neutral alleles.


There are several methods to compute this percentage. The two main ways are the path method [ 47 ] [ 43 ]  and the tabular method. [ 48 ] [ 49 ]


Typical coancestries between relatives are as follows:


Breeding in domestic animals is primarily  assortative  breeding (see  selective breeding ). Without the sorting of individuals by trait, a breed could not be established, nor could poor genetic material be removed.
 Homozygosity  is the case where similar or identical alleles combine to express a trait that is not otherwise expressed (recessiveness). Inbreeding exposes recessive alleles through increasing homozygosity. [ 59 ]


Breeders must avoid breeding from individuals that demonstrate either homozygosity or heterozygosity for disease causing alleles. [ 60 ]  The goal of preventing the transfer of deleterious alleles may be achieved by reproductive isolation,  sterilization , or, in the extreme case,  culling . Culling is not strictly necessary if genetics are the only issue in hand. Small animals such as cats and dogs may be sterilized, but in the case of large agricultural animals, such as cattle, culling is usually the only economic option.


The issue of casual breeders who inbreed irresponsibly is discussed in the following quotation on cattle:


Meanwhile, milk production per cow per lactation increased from 17,444 lbs to 25,013 lbs from 1978 to 1998 for the Holstein breed. Mean breeding values for milk of Holstein cows increased by 4,829 lbs during this period. [ 61 ]  High producing cows are increasingly difficult to breed and are subject to higher health costs than cows of lower genetic merit for production (Cassell, 2001).


Intensive selection for higher yield has increased relationships among animals within breed and increased the rate of casual inbreeding.


Many of the traits that affect profitability in crosses of modern dairy breeds have not been studied in designed experiments. Indeed, all crossbreeding research involving North American breeds and strains is very dated (McAllister, 2001) if it exists at all. [ 62 ]


As a result of long-term cooperation between  USDA  and dairy farmers which led to a revolution in dairy cattle productivity, the United States has since 1992 been the world’s largest supplier of dairy bull semen. [ 63 ]   However, US genomic technology has resulted in the US dairy cattle population becoming "the most inbred it’s ever been" and the rate of increase in US national milk yield has tapered off.  Efforts are now being made to identify desirable genes in cattle breeds not yet optimized by US dairy breeders in order to apply  hybrid vigor  to the US dairy cattle population and thus propel US dairy technology to even higher levels of productivity.


The BBC produced two documentaries on dog inbreeding titled  Pedigree Dogs Exposed  and  Pedigree Dogs Exposed: Three Years On  that document the negative health consequences of excessive inbreeding.


Linebreeding is a form of inbreeding. There is no clear distinction between the two terms, but linebreeding may encompass crosses between individuals and their descendants or two cousins. [ 58 ] [ 64 ]  This method can be used to increase a particular animal's contribution to the population. [ 58 ]  While linebreeding is less likely to cause problems in the first generation than does inbreeding, over time, linebreeding can reduce the genetic diversity of a population and cause problems related to a too-small gene pool that may include an increased prevalence of genetic disorders and inbreeding depression. [ citation needed ]


Outcrossing is where two unrelated individuals are crossed to produce progeny. In outcrossing, unless there is verifiable genetic information, one may find that all individuals are distantly related to an ancient progenitor. If the trait carries throughout a population, all individuals can have this trait. This is called the  founder effect . In the well established breeds, that are commonly bred, a large gene pool is present. For example, in 2004, over 18,000 Persian cats were registered. [ 65 ]  A possibility exists for a complete outcross, if no barriers exist between the individuals to breed. However, it is not always the case, and a form of distant linebreeding occurs. Again it is up to the assortative breeder to know what sort of traits, both positive and negative, exist within the diversity of one breeding. This diversity of genetic expression, within even close relatives, increases the variability and diversity of viable stock.


Systematic inbreeding and maintenance of inbred strains of  laboratory mice  and rats is of great importance for biomedical research. The inbreeding guarantees a consistent and uniform  animal model  for experimental purposes and enables genetic studies in  congenic  and knock-out animals. In order to achieve a mouse strain that is considered inbred, a minimum of 20 sequential generations of sibling matings must occur. With each successive generation of breeding, homozygosity in the entire genome increases, eliminating heterozygous loci. With 20 generations of sibling matings, homozygosity is occurring at roughly 98.7% of all loci in the genome, allowing for these offspring to serve as animal models for genetic studies. [ 66 ]  The use of inbred strains is also important for genetic studies in animal models, for example to distinguish genetic from environmental effects. The mice that are inbred typically show considerably lower survival rates.


Inbreeding increases homozygosity, which can increase the chances of the expression of deleterious or beneficial recessive alleles  and therefore has the potential to either decrease or increase the fitness of the offspring. Depending on the rate of inbreeding, natural selection may still be able to eliminate deleterious alleles. [ 68 ]  With continuous inbreeding, genetic variation is lost and homozygosity is increased, enabling the expression of recessive deleterious alleles in homozygotes. The  coefficient of inbreeding , or the degree of inbreeding in an individual, is an estimate of the percent of homozygous alleles in the overall genome. [ 69 ]  The more biologically related the parents are, the greater the coefficient of inbreeding, since their genomes have many similarities already. This overall homozygosity becomes an issue when there are deleterious recessive alleles in the gene pool of the family. [ 70 ]  By pairing chromosomes of similar genomes, the chance for these recessive alleles to pair and become homozygous greatly increases, leading to offspring with autosomal recessive disorders. [ 70 ]  However, these deleterious effects are common for very close relatives but not for those related on the 3rd cousin or greater level, who exhibit increased fitness. [ 2 ]


Inbreeding is especially problematic in small populations where the genetic variation is already limited. [ 71 ]  By inbreeding, individuals are further decreasing genetic variation by increasing homozygosity in the genomes of their offspring. [ 72 ]  Thus, the likelihood of deleterious recessive alleles to pair is significantly higher in a small inbreeding population than in a larger inbreeding population. [ 71 ]


The fitness consequences of consanguineous mating have been studied since their scientific recognition by  Charles Darwin  in 1839. [ 73 ] [ 74 ]   Some of the most harmful effects known from such breeding includes its effects on the mortality rate as well as on the general health of the offspring. [ 75 ]  Since the 1960s, there have been many studies to support such debilitating effects on the human organism. [ 72 ] [ 73 ] [ 75 ] [ 76 ] [ 77 ]  Specifically, inbreeding has been found to decrease fertility as a direct result of increasing homozygosity of deleterious recessive alleles. [ 77 ] [ 78 ]  Fetuses produced by inbreeding also face a greater risk of spontaneous abortions due to inherent complications in development. [ 79 ]  Among mothers who experience stillbirths and early infant deaths, those that are inbreeding have a significantly higher chance of reaching repeated results with future offspring. [ 80 ]  Additionally, consanguineous parents possess a high risk of premature birth and producing underweight and undersized infants. [ 81 ]  Viable inbred offspring are also likely to be inflicted with physical deformities and genetically inherited diseases. [ 69 ]  Studies have confirmed an increase in several genetic disorders due to inbreeding such as blindness, hearing loss, neonatal diabetes, limb malformations,  disorders of sex development , schizophrenia and several others. [ 69 ] [ 82 ]  Moreover, there is an increased risk for congenital heart disease depending on the inbreeding coefficient (See  coefficient of inbreeding ) of the offspring, with significant risk accompanied by an F =.125 or higher. [ 27 ]


The general negative outlook and eschewal of inbreeding that is prevalent in the  Western world  today has roots from over 2000 years ago.  Specifically, written documents such as the Bible illustrate that there have been laws and social customs that have called for the abstention from inbreeding.  Along with cultural taboos, parental education and awareness of inbreeding consequences have played large roles in minimizing inbreeding frequencies in areas like Europe.  That being so, there are less urbanized and less populated regions across the world that have shown continuity in the practice of inbreeding.


The continuity of inbreeding is often either by choice or unavoidably due to the limitations of the geographical area. When by choice, the rate of consanguinity is highly dependent on religion and culture. [ 71 ]  In the Western world, some  Anabaptist  groups are highly inbred because they originate from small founder populations that have bred as a closed population. [ 83 ]


Of the practicing regions, Middle Eastern and northern Africa territories show the greatest frequencies of consanguinity. [ 71 ]


Among these populations with high levels of inbreeding, researchers have found several disorders prevalent among inbred offspring.  In  Lebanon ,  Saudi Arabia ,  Egypt , and in  Israel , the offspring of consanguineous relationships have an increased risk of congenital malformations, congenital heart defects, congenital  hydrocephalus  and  neural tube defects . [ 71 ]   Furthermore, among inbred children in  Palestine  and Lebanon, there is a positive association between consanguinity and reported  cleft lip/palate  cases. [ 71 ]   Historically, populations of  Qatar  have engaged in consanguineous relationships of all kinds, leading to high risk of inheriting genetic diseases.  As of 2014, around 5% of the Qatari population suffered from hereditary hearing loss; most were descendants of a consanguineous relationship. [ 84 ]


Inter-nobility  marriage  was used as a method of forming  political alliances  among elites. These ties were often sealed only upon the birth of progeny within the  arranged marriage . Thus marriage was seen as a union of lines of nobility and not as a contract between individuals.


Royal intermarriage  was often practiced among European royal families, usually for interests of state. Over time, due to the relatively limited number of potential consorts, the  gene pool  of many ruling families grew progressively smaller, until all European royalty was related. This also resulted in many being descended from a certain person through many lines of descent, such as the numerous European royalty and nobility descended from the British  Queen Victoria  or  King Christian IX of Denmark . [ 85 ]  The House of  Habsburg  was known for its intermarriages;  the  Habsburg lip  often cited as an ill-effect.  The closely related houses of Habsburg,  Bourbon ,  Braganza  and  Wittelsbach  also frequently engaged in first-cousin unions as well as the occasional  double-cousin  and uncle–niece marriages.


In  ancient Egypt , royal women were believed to carry the bloodlines and so it was advantageous for a  pharaoh  to marry his sister or half-sister; [ 86 ]  in such cases a special combination between  endogamy  and  polygamy  is found. Normally, the old ruler's eldest son and daughter (who could be either siblings or half-siblings) became the new rulers. All rulers of the  Ptolemaic dynasty  uninterruptedly from  Ptolemy IV  ( Ptolemy II  married his sister but had no issue) were married to their brothers and sisters, so as to keep the Ptolemaic blood "pure" and to strengthen the line of succession. King  Tutankhamun 's mother is reported to have been the half-sister to his father, [ 87 ]   Cleopatra VII  (also called Cleopatra VI) and  Ptolemy XIII , who married and became co-rulers of  ancient Egypt  following their father's death, are the most widely known example. [ 88 ]


An  incest taboo   is any  cultural rule  or  norm  that prohibits  sexual relations  between certain members of the same  family , mainly between individuals  related by blood .  All known human cultures  have norms that exclude certain close relatives from those considered suitable or permissible  sexual  or  marriage  partners, making such relationships  taboo . However, different norms exist among cultures as to which blood relations are permissible as sexual partners and which are not. Sexual relations between related persons which are subject to the taboo are called  incestuous relationships .


Some cultures proscribe sexual relations between  clan -members, even when no traceable biological relationship exists, while members of other clans are permissible irrespective of the existence of a biological relationship. In many cultures, certain types of cousin relations are preferred as sexual and marital partners, whereas in others these are taboo. Some cultures permit sexual and marital relations between aunts/uncles and nephews/nieces. In some instances, brother–sister marriages have been practised by the  elites  with some regularity. Parent–child and sibling–sibling unions are almost universally taboo. [ 1 ]


Debate about the origin of the incest taboo has often been framed as a question of whether it is based in  nature or nurture .


One explanation sees the incest taboo as a cultural implementation of a biologically evolved preference for sexual partners with whom one is unlikely to share genes, since  inbreeding  may have detrimental outcomes. The most widely held hypothesis proposes that the so-called  Westermarck effect  discourages adults from engaging in sexual relations with individuals with whom they grew up. The existence of the Westermarck effect has achieved some empirical support. [ 2 ]


Another school argues that the incest prohibition is a cultural construct which arises as a side effect of a general human preference for group  exogamy , which arises because intermarriage between groups construct valuable  alliances  that improve the ability for both groups to thrive. According to this view, the incest taboo is not necessarily universal, but is likely to arise and become more strict under cultural circumstances that favour exogamy over  endogamy , and likely to become more lax under circumstances that favor endogamy. This hypothesis has also achieved some empirical support. [ citation needed ]


While it is theoretically possible that  natural selection  may, under certain  genetic  circumstances, select for individuals that  instinctively  avoid mating with (close) relatives, incest will still exist in the gene pool because even genetically weakened,  inbred  individuals are better watchposts against  predators  than none at all, and weak individuals are useful for the stronger individuals in the group as looking out for predators without being able to seriously compete with the stronger individuals. [ 3 ] [ 4 ] [ dubious  –  discuss ]  Additionally, protecting the health of closer relatives and their inbred offspring is more evolutionarily advantageous than punishing said relative, especially in a context where predation and  starvation  are significant factors, as opposed to a rich  welfare state . [ 5 ] [ 6 ]


Modern  anthropology  developed at a time when a great many human societies were illiterate, and much of the research on incest taboos has taken place in societies without legal codes, and, therefore, without written laws concerning marriage and incest. Nevertheless, anthropologists have found that the institution of marriage, and rules concerning appropriate and inappropriate sexual behavior, exist in every society. [ 7 ]  The following excerpt from  Notes and Queries on Anthropology  (1951), a well-established field manual for  ethnographic  research, illustrates the scope of ethnographic investigation into the matter:


Incest is sexual intercourse between individuals related in certain prohibited degrees of  kinship .  In every society there are rules prohibiting incestuous unions, both as to sexual intercourse and recognized marriage. The two prohibitions do not necessarily coincide. There is no uniformity as to which degrees are involved in the prohibitions. The rules regulating incest must be investigated in every society by means of the  genealogical method . The prohibition may be so narrow as to include only one type of parent–child relationship (though this is very rare), or those within the elementary family; or so wide as to include all with whom genealogical or classificatory kinship can be traced. The more usual practice is that unions with certain relatives only are considered incestuous, the relationships being regulated by the type of descent emphasized. In some societies unions with certain persons related by  affinity  are also considered incestuous.
What penalties fall on (a) the individuals concerned; (b) the community as a whole? Are such penalties enforced by authority, or are they believed to ensue automatically by the action of a supernatural force?  Is there any correlation between the severity of the penalty and the nearness of the blood-tie of the partners in guilt? Should children be born as the result of incestuous unions, how are they treated? Are there any methods, ritual or legal, by which persons who fall within the prohibited degrees and wish to marry can break the relationship and become free to marry? [ 8 ]


These theories anthropologists are generally concerned solely with brother–sister incest, and are not claiming that all sexual relations among family members are taboo or even necessarily considered incestuous by that society. [ citation needed ]  These theories are further complicated by the fact that in many societies people related to one another in different ways, and sometimes distantly, are classified together as siblings, and others who are just as closely related genetically are not considered family members.


The definition restricts itself to sexual intercourse; this does not mean that other forms of sexual contact do not occur, or are proscribed, or prescribed. For example, in some Inuit societies in the Arctic, and traditionally in  Bali , mothers would routinely stroke the penises of their infant sons; such behavior was considered no more sexual than breastfeeding. [ 9 ] [ 10 ]


In these theories, anthropologists are primarily concerned with marriage rules and not actual sexual behavior. In short, anthropologists were not studying "incest" per se; they were asking informants what they meant by "incest", and what the consequences of "incest" were, in order to map out social relationships within the community. [ citation needed ]


This excerpt also suggests that the relationship between sexual and marriage practices is complex, and that societies distinguish between different sorts of prohibitions. In other words, although an individual may be prohibited from marrying or having sexual relations with many people, different sexual relations may be prohibited for different reasons, and with different penalties.


For example,  Trobriand Islanders  prohibit both sexual relations between a woman and her brother, [ 11 ]  and between a woman and her father, [ 12 ]  but they describe these prohibitions in very different ways: relations between a woman and her brother fall within the category of forbidden relations among members of the same clan; relations between a woman and her father do not. [ 12 ]  This is because the Trobrianders are matrilineal; children belong to the clan of their mother and not of their father. Thus, sexual relations between a man and his mother's sister (and mother's sister's daughter) are also considered incestuous, but relations between a man and his father's sister are not. [ 13 ]   A man and his father's sister will often have a flirtatious relationship, and, far from being taboo, Trobriand society encourages a man and his father's sister or the daughter of his father's sister to have sexual relations or marry. [ 14 ]


An explanation for the taboo is that it is due to an instinctual, inborn aversion that would lower the adverse  genetic effects  of  inbreeding  such as a higher incidence of congenital  birth defects  (see article  Inbreeding depression ). Since the rise of modern genetics, belief in this theory has grown. [ 15 ] [ 16 ] [ 17 ] [ 18 ] [ failed verification ]


The increase in frequency of birth defects often attributed to inbreeding results directly from an increase in the frequency of homozygous alleles inherited by the offspring of inbred couples. [ 19 ]  This leads to an increase in homozygous allele frequency within a population, and results in diverging effects. Should a child inherit the version of homozygous alleles responsible for a birth defect from its parents, the birth defect will be expressed; on the other hand, should the child inherit the version of homozygous alleles not responsible for a birth defect, it would actually decrease the ratio of the allele version responsible for the birth defect in that population. The overall consequences of these diverging effects depends in part on the size of the population.


In small populations, as long as children born with inheritable birth defects die (or are killed) before they reproduce, the ultimate effect of inbreeding will be to  decrease  the frequency of defective genes in the population; over time, the gene pool will be healthier. However, in larger populations, it is more likely that large numbers of carriers will survive and mate, leading to more constant rates of birth defects. [ 20 ]  Besides recessive genes, there are also other reasons why inbreeding may be harmful, such as a narrow range of certain  immune systems  genes in a population increasing vulnerability to infectious diseases (see  Major histocompatibility complex and sexual selection ). The biological costs of incest also depend largely on the degree of genetic proximity between the two relatives engaging in incest. This fact may explain why the cultural taboo generally includes prohibitions against sex between close relatives but less often includes prohibitions against sex between more distal relatives. [ 21 ]  Children born of close relatives have decreased survival. [ 17 ] [ 18 ]  Many mammal species, including humanity's closest  primate  relatives, avoid incest. [ 2 ]


The  Westermarck effect , first proposed by  Edvard Westermarck  in 1891, is the theory that children reared together, regardless of biological relationship, form a sentimental attachment that is by its nature non-erotic. [ 22 ]   Melford Spiro  argued that his observations that unrelated children reared together on Israeli Kibbutzim nevertheless avoided one another as sexual partners confirmed the Westermarck effect. [ 23 ]  Joseph Shepher in a study examined the second generation in a  kibbutz  and found no marriages and no sexual activity between the adolescents in the same peer group. This was not enforced but voluntary. Looking at the second generation adults in all kibbutzim, out of a total of 2769 marriages, none were between those of the same peer group. [ 24 ]


However, according to a book review by John Hartung of a book by Shepher, out of 2516 marriages documented in Israel, 200 were between couples reared in the same kibbutz. These marriages occurred after young adults reared on kibbutzim had served in the military and encountered tens of thousands of other potential mates, and 200 marriages is higher than what would be expected by chance. Of these 200 marriages, five were between men and women who had been reared together for the first six years of their lives, which would argue against the Westermarck effect. [ 25 ]


A study in Taiwan of marriages where the future bride is adopted in the groom's family as an infant or small child found that these marriages have higher infidelity and divorce and lower fertility than ordinary marriages; it has been argued that this observation is consistent with the Westermarck effect. [ 26 ]


Another approach is looking at moral objections to third-party incest. This increases the longer a child has grown up together with another child of the opposite sex. This occurs even if the other child is genetically unrelated. [ 18 ]  Humans have been argued to have a special kin detection system that besides the incest taboo also regulates a tendency towards  altruism  towards kin. [ 27 ]


One objection against an instinctive and genetic basis for the incest taboo is that incest does occur. [ 28 ] [ 29 ] [ 30 ]  Anthropologists have also argued that the social construct "incest" (and the incest taboo) is not the same thing as the biological phenomenon of "inbreeding". For example, there is equal genetic relation between a man and the daughter of his father's sister and between a man and the daughter of his mother's sister, such that biologists would consider mating incestuous in both instances, but  Trobrianders  consider mating incestuous in one case and not in the other. Anthropologists have documented a great number of societies where marriages between some first cousins are prohibited as incestuous, while marriages between other first cousins are encouraged. Therefore, it is argued that the prohibition against incestuous relations in most societies is not based on or motivated by concerns over biological closeness. [ 31 ]  Other studies on cousin marriages have found support for a biological basis for the taboo. [ 32 ] [ 33 ] [ 34 ]  Also, current supporters of genetic influences on behavior do not argue that genes determine behavior absolutely, but that genes may create predispositions that are affected in various ways by the environment (including culture). [ 35 ]


Steve Stewart-Williams argues against the view that incest taboo is a Western phenomenon, arguing that while brother–sister marriage was reported in a diverse range of cultures such Egyptian, Incan, and Hawaiian cultures, it was not a culture-wide phenomenon, being largely restricted to the upper classes. Stewart-Williams argues that these marriages were largely political (their function being to keep power and wealth concentrated in the family) and there is no evidence the siblings were attracted to each other and there is in fact some evidence against it (for example,  Cleopatra  married two of her brothers but did not have children with them, only having children with unrelated lovers). Stewart-Williams suggests that this was therefore simply a case of social pressure overriding anti-incest instincts. Stewart-Williams also observes that anti-incest behaviour has been observed in other animals and even many plant species (many plants could self-pollinate but have mechanisms that prevent them from doing so). [ 36 ]


Psychoanalytic theory —in particular, the claimed existence of an  Oedipus complex , which is not an instinctual aversion against incest but an instinctual desire—has influenced many theorists seeking to explain the incest taboo using sociological theories. [ 2 ]


The anthropologist  Claude Lévi-Strauss  developed a general argument for the universality of the incest taboo in human societies. His argument begins with the claim that the incest taboo is in effect a prohibition against  endogamy , and the effect is to encourage  exogamy . Through exogamy, otherwise unrelated households or lineages will form relationships through marriage, thus strengthening social solidarity. That is, Lévi-Strauss views marriage as an exchange of women between two social groups. This theory is based in part on  Marcel Mauss 's theory of  The Gift , which (in Lévi-Strauss' words) argued:


that exchange in primitive societies consists not so much in economic transactions as in reciprocal gifts, that these reciprocal gifts have a far more important function than in our own, and that this primitive form of exchange is not merely nor essentially of an economic nature but is what he aptly calls "a total social fact", that is, an event which has a significance that is at once social and religious, magic and economic, utilitarian and sentimental, jural and moral. [ 37 ]


It is also based on Lévi-Strauss's analysis of data on different kinship systems and marriage practices documented by anthropologists and historians. Lévi-Strauss called attention specifically to data collected by  Margaret Mead  during her research among the  Arapesh . When she asked if a man ever sleeps with his sister, Arapesh replied: "No we don't sleep with our sisters; we give our sisters to other men, and other men give us their sisters." Mead pressed the question repeatedly, asking what would happen if a brother and sister did have sex with one another. Lévi-Strauss quotes the Arapesh response:


What? You would like to marry your sister? What is the matter with you anyway? Don't you want a brother-in-law? Don't you realize that if you marry another man's sister and another man marries your sister, you will have at least two brothers-in-law, while if you marry your own sister, you will have none? With whom will you hunt, with whom will you garden, whom will you visit? [ 38 ]


By applying Mauss's theory to data such as Mead's, Lévi-Strauss proposed what he called  alliance theory . He argued that, in "primitive" societies—societies not based on agriculture, class hierarchies, or centralized government—marriage is not fundamentally a relationship between a man and a woman, but a transaction involving a woman that forges a relationship—an alliance—between two men. [ 39 ]


Some anthropologists argue that nuclear family incest avoidance can be explained in terms of the ecological, demographic, and economic benefits of exogamy. [ 40 ]


While Lévi-Strauss generally discounted the relevance of alliance theory in Africa, a particularly strong concern for incest is a fundamental issue among the age systems of East Africa. Here, the avoidance between men of an age-set and their daughters is altogether more intense than in any other sexual avoidance. Paraphrasing Lévi-Strauss's argument, without this avoidance, the rivalries for power between age-sets, coupled with the close bonds of sharing between age-mates, could lead to a sharing of daughters as spouses. Young men entering the age system would then find a dire shortage of marriageable girls, and extended families would be in danger of dying out. Thus, by parading this avoidance of their daughters, senior men make these girls available for younger age-sets and their marriages form alliances that mitigate the rivalries for power. [ 41 ]


Exogamy between households or descent groups is typically prescribed in  classless societies . Societies that are stratified—that is, divided into unequal classes—often prescribe different degrees of endogamy. Endogamy is the opposite of exogamy; it refers to the practice of marriage between members of the same social group. An example is  India's caste system , in which unequal castes are endogamous. [ 42 ]  Inequality between  ethnic groups  and  races  also correlates with endogamy. [ 43 ]


An extreme example of this principle, and an exception to the incest taboo, is found among members of the ruling class in certain ancient states, such as the Inca, Egypt, China, and Hawaii; brother–sister marriage (usually between half-siblings) was a means of maintaining wealth and political power within one family. [ 44 ]  Some scholars have argued that in Roman-governed Egypt this practice was also found among commoners, [ 45 ] [ 46 ] [ 47 ] [ 48 ]  but others have argued that this was in fact not the norm. [ 49 ] [ 50 ] [ 51 ]


Infertility and childlessness stigmas  are social and cultural codes that identify the inability to have children as a disgraceful state of being. Broadly speaking, in many cultures, "Demonstrating fertility is necessary to be considered a full adult, a real man or woman, and to leave a legacy after death," and thus the failure to make this demonstration is penalized. [ 1 ]  Both  male infertility  and  female infertility  can be  stigmatized , however, in many traditional cultures, women are held responsible for child-rearing and thus for pregnancy or the lack thereof.  Infertility  and  childlessness  stigmas are related to disability or physical-deformity stigmas and violation-of-group-norm stigmas. Infertility is a "deeply intimate matter, often deemed as  taboo  to discuss publicly." [ 2 ]


Infertility and childlessness can have negative social, [ 2 ]  psychological [ 2 ]  and economic consequences, [ 3 ]  including "discrimination,  social exclusion , and abandonment." [ 4 ]  Adults without children may be subject to derisive language, intrusive questioning, shaming, [ 3 ]  ostracism, and physical abuse. [ 5 ]  Other negative consequences of the infertility–childlessness stigma, especially for women, may include depression, low self-esteem, [ 6 ]  and even suicidal ideation or suicide. [ 5 ]  People with infertility living in societies where it is a stigmatized condition may suffer from anxiety, may choose to self-isolate, and may become secretive or withdrawn. [ 7 ]  In  pro-natalist  societies,  voluntary childlessness  is often considered a  deviant behavior . [ 7 ]


Stigmas may be particularly acute in communities that  organize themselves collectively  and thus place a high value on clan, lineage and perpetuation of family legacy. [ 2 ]  In these cultures, childlessness may be viewed as a "tragedy for the whole community" beyond the personal significance for infertile or childless individuals. [ 2 ]  However, even in a prototypically  individualistically organized society , 42 percent of women tested in a study of the emotional consequences of infertility were found to have "global distress levels in the clinically significant range," in part due to social norms that judge women without children to be "unnatural and selfish." [ 8 ]


Most academic study of infertility addresses expensive treatment technologies, rather than the " anthropological  and  public health " effects. [ 3 ]  In more-developed countries, the widespread availability of  assisted reproductive technologies  has "transformed infertility from an acute, private agony that was accepted as fate, into a chronic, public stigma from which there were costly, and often unfulfilled hopes, of deliverance." [ 9 ]  In some cultures, biomedical explanations for infertility may be disregarded in favor of traditional beliefs that past wrong choices have resulted in the placement of an infertility  curse , thus accelerating the  vicious cycle  of stigma. [ 2 ]  Blame may assigned, variously, to having offended gods or ancestors, abortions in a past life, [ 2 ]  practicing witchcraft, past promiscuity, use of birth control, [ 1 ]  wrong living generally, etc. Exclusion of the infertile or childlessness from social events is known, enacted as a means of quarantine to prevent the "contagion" or "toxin" of non-reproduction from spreading within the community. [ 5 ]  Infertile people are also viewed as sad people who may bring  sadness  with them and "spoil" celebrations. [ 5 ]


As one scholar put it, "Like  leprosy  and  epilepsy , infertility bears an ancient social stigma. [ 7 ]  An archaic term for the condition of female infertility, present in the Old Testament, is  barren woman . [ 10 ]  There have been three traditional means of addressing infertility: [ 2 ]


In some societies, women with children are allowed access to certain community resources and privileges from which childless women may be excluded, thus children act as a sort of universal passport to humanity. [ 5 ] [ 13 ]


In some cultures, funeral practices for childless women are different from those for women who successfully conceived and bore offspring. [ 3 ]  Notably, "In the Hindu religion, a woman without a child, particularly a son, can't go to heaven. Sons perform death rituals." [ 5 ]  In Catholicism, there is a  limbo of infants  for stillborn babies (as  baptism  is a  sacrament  available only to the living), thus women unable to bring a pregnancy to term would be told they would not encounter their children's souls in an afterlife. [ 14 ]  The original doctrine was that these fetuses or babies were consigned to hell, resulting in a latter-day practice called  respite sanctuaries . [ 15 ]  In the traditional Vietnamese belief system, childlessness risks destroying "the entire  âm  realm of one's ancestors and consequently scatters all ancestral  linh hon  into wandering ghosts and demons ( ma qüy )." [ 16 ]


An individual's ability to deflect or resist stigma may depend on array of intersecting age, gender, class, economic, and/or psychological factors. [ 17 ]


A study of infertility experiences in Zambia concluded: [ 1 ]


Stigma cannot be broken in silence. Healthcare policies and education should increase discussion of infertility without shaming infertile people. Men may have more power in their communities; their experiences must be included.


Irish kinship  is a system of  kinship terminology  (descended from the original  Celtic  practices) which shows a bifurcate collateral pattern. This system is used by a minority of people living in the  Gaeltacht  regions of Ireland. Irish  kinship  terminology varies from English kinship as it focuses on gender and generation, [ 1 ]  with less emphasis on differentiating lineal vs. collateral. [ 2 ]


Irish kinship is limited to a small number of words of  Gaelic  origin used in identifying relatives: [ 3 ]


A majority of the terms used in the kinship system are similar to the English kinship system, but the terms for aunt, uncle, nephew, niece and cousin have a far vaguer and different use. These terms, however, vary in degree of use as this system is largely confined to the Gaeltacht regions, and hence not widely used among other members of Irish society. [ 4 ]  The system has, however, been previously taught in primary schools around the country, including in non-Gaeltacht areas.


Aintin  is the word for "aunt" and  uncail  for "uncle" but in the Irish kinship system aunt and uncle have a wider definition; in common kinship an aunt or uncle is the sister or brother of either the mother or the father. However, in Irish kinship,  Aintin  and  Uncail  are used for not only the siblings of the parents, but as well for any relative whose age is of a great distance from the child. This effectively means the cousin of a parent is called an aunt or uncle, while those who are aged or in their senior years (aunts or uncles of a parent, or cousins of a grandparent) are termed  Seanaintin  and  Seanuncail  ( great aunt  and great uncle). Using this system, the children of cousins in a person’s own generation (however distant) are called nephews and nieces, using the terms  Nia  and  Neacht. [ 5 ]  Grandchildren of brothers, sisters or cousins of the same generation are termed  Garnia  (great-nephew) or  Garneacht  (great-niece).


Col Gaolta  is a word for cousin; in the Irish kinship system, this word is used for all relatives in one's generation or those near your age, except in the case of a brother or a sister. The word actually means  related by blood . [ 6 ]


Mo Mhuintir, being Irish for  My People , is a vague term used for relatives people believe they are related to, but do not have enough information to determine how. [ 2 ]


Iroquois kinship  (also known as  bifurcate merging ) is a  kinship  system named after the  Haudenosaunee  people, also known as the  Iroquois , whose kinship system was the first one described to use this particular type of system.  Identified by  Lewis Henry Morgan  in his 1871 work  Systems of Consanguinity and Affinity of the Human Family , the Iroquois system is one of the six major kinship systems ( Eskimo ,  Hawaiian , Iroquois,  Crow ,  Omaha , and  Sudanese ). [ 1 ]


The system has both  classificatory  and  descriptive  terms.  In addition to gender and generation, Iroquois kinship also distinguishes 'same-sex' and 'cross-sex' parental siblings: the brothers of Ego's (the subject from whose perspective the kinship is based) father, and the sisters of Ego's mother, are referred to by the same parental kinship terms used for Ego's Father and Mother. The sisters of Ego's father, and the brothers of Ego's mother, on the other hand, are referred to by non-parental kinship terms, commonly translated into English as "Aunt" and "Uncle".


The children of one's parents' same-sex siblings, i.e.  parallel cousins , are referred to by sibling kinship terms. The children of Aunts or Uncles, i.e.  cross cousins , are not considered siblings, and are referred to by kinship terms commonly translated into English as "cousin".  In some systems, the kinship terms applied to cross-cousins are the same as those applied to brothers-in-law and sisters-in-law, due to preferential marriage practices (see below).


Ego (the subject from whose perspective the kinship is based) is encouraged to marry his  cross-cousins  but discouraged or prohibited from marrying his  parallel cousins .  In many societies with Iroquois kinship terminologies, the preferred marriage partners include not only first cousins (mother's brother's children and father's sister's children), but more remote relatives who are also classified as cross-cousins by the logic of the kinship system.  Preferential cross-cousin marriage can be useful in reaffirming alliances between unilineal  lineages  or  clans .


The term Iroquois comes from the six  Iroquois  tribes of northeastern North America. Another aspect of their kinship was that the six tribes all had  matrilineal  systems, in which children were born into the mother's  clan  and gained status through it. Women controlled some property, and hereditary leadership passed through the maternal line. A woman's eldest brother was more important as a mentor to her children than their father, who was always of a different clan.


"Iroquois tradition had the lineage of the clan or tribe traced through the mother's side. However, the amount of power women held in the tribe decreased with time due to the American revolution." [ 2 ]  (Lappas, Thomas).


Some groups in other countries also happen to be independently organized for kinship by the Iroquois system.  It is commonly found in  unilineal descent  groups.  These include:


Other populations found to have the Iroquois system are


Some communities in   South India  use the kinship tradition described above. [ 3 ]


Many of the cultures of  Vanuatu  use this type of kinship system. In  Bislama  (Vanuatu pidgin), paternal uncles and maternal aunts are referred to as  smol papa  "small father" and  smol mama  "small mother" respectively.