Pedigree collapseIn genealogy, pedigree collapse describes how reproduction between two individuals who share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be. Robert C. Gunderson coined the term; synonyms include implex and the German Ahnenschwund (loosely translated: "loss of lineage"). Without pedigree collapse, a person's ancestor tree is a binary tree, formed by the person, the parents (2), the grandparents (4), great-grandparents (8), and so on.
Parallel and cross cousinsIn discussing consanguineal kinship in anthropology, a parallel cousin or ortho-cousin is a cousin from a parent's same-sex sibling, while a cross-cousin is from a parent's opposite-sex sibling. Thus, a parallel cousin is the child of the father's brother (paternal uncle's child) or of the mother's sister (maternal aunt's child), while a cross-cousin is the child of the mother's brother (maternal uncle's child) or of the father's sister (paternal aunt's child). Where there are unilineal descent groups in a society (i.
AmishThe Amish (ˈɑːmᵻʃ; Amisch; Amische), formally the Old Order Amish, are a group of traditionalist Anabaptist Christian church fellowships with Swiss German and Alsatian origins. They are closely related to Mennonite churches, a separate Anabaptist denomination. The Amish are known for simple living, plain dress, Christian pacifism, and slowness to adopt many conveniences of modern technology, with a view neither to interrupt family time, nor replace face-to-face conversations whenever possible, and a view to maintain self-sufficiency.
ConsanguinityConsanguinity ("blood relation", from Latin consanguinitas) is the characteristic of having a kinship with a relative who is descended from a common ancestor. Many jurisdictions have laws prohibiting people who are related by blood from marrying or having sexual relations with each other. The degree of consanguinity that gives rise to this prohibition varies from place to place. Such rules are also used to determine heirs of an estate according to statutes that govern intestate succession, which also vary from jurisdiction to jurisdiction.
Coefficient of relationshipThe coefficient of relationship is a measure of the degree of consanguinity (or biological relationship) between two individuals. The term coefficient of relationship was defined by Sewall Wright in 1922, and was derived from his definition of the coefficient of inbreeding of 1921. The measure is most commonly used in genetics and genealogy. A coefficient of inbreeding can be calculated for an individual, and is typically one-half the coefficient of relationship between the parents.
IncestIncest (ˈɪnsɛst ) is human sexual activity between family members or close relatives. This typically includes sexual activity between people in consanguinity (blood relations), and sometimes those related by affinity (marriage or stepfamily), adoption, or lineage. It is strictly forbidden and considered immoral in most societies, and can lead to an increased risk of genetic disorders in children. The incest taboo is one of the most widespread of all cultural taboos, both in present and in past societies.
Incest tabooAn 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 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.
EndogamyEndogamy is the cultural practice of mating—usually in the form of marriage—within a specific social group, religious denomination, caste, or ethnic group, rejecting those from others as unsuitable for marriage or other close interpersonal relationships. Whereas endogamy refers to marriage within the group, its opposite, exogamy, describes the social norm of marriage outside of the group. Endogamy is common in many cultures and ethnic groups.
InbreedingInbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. 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 incest only rarely. Inbreeding results in homozygosity, which can increase the chances of offspring being affected by recessive traits.
Inbreeding depressionInbreeding depression is the reduced biological fitness which has the potential to result from inbreeding (the breeding of related individuals). Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression, though inbreeding and outbreeding depression can simultaneously occur.
