consanguinity (kŏnˌsăng-gwĭnˈĭtē) [key], state of being related by blood or descended from a common ancestor. This article focuses on legal usage of the term as it relates to the laws of marriage, descent, and inheritance; for its broader anthropological implications, see incest. Consanguinity is to be distinguished from affinity, which is the relation of a person, through marriage, to the consanguineous relatives of a spouse. Marriage between persons in lineal consanguinity (persons in the direct line of descent, such as father and daughter) and between brothers and sisters is void under common law, church law, and statute. Whether or not marriages between persons of collateral consanguinity (those having a common ancestor but not related in direct line of descent) are prohibited as incestuous depends on statutory provision and judicial interpretation. In more than half the states of the United States, marriage between first cousins is prohibited by law, and the Roman Catholic Church and the Orthodox Eastern Church have strict rules on consanguinity as an impediment to marriage. Statutes in the United States discard affinal relationship as an impediment to marriage. Whether incestuous marriages are void or voidable in the United States depends on local statutes and their interpretation. In the law of descent and inheritance, the concept of consanguinity is most important in the area of intestate succession. Most states award the spouse of a person who dies intestate a certain share of the estate, even though there exists neither lineal nor collateral consanguinity between the spouses.
See B. D. Inglis, Family Law (2d ed., 2 vol., 1968–70).