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.
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.
AnnulmentAnnulment is a legal procedure within secular and religious legal systems for declaring a marriage null and void. Unlike divorce, it is usually retroactive, meaning that an annulled marriage is considered to be invalid from the beginning almost as if it had never taken place (though some jurisdictions provide that the marriage is only void from the date of the annulment; for example, this is the case in section 12 of the Matrimonial Causes Act 1973 in England and Wales).
