NUCLEAR FAMILY

also called elementary family in sociology and anthropology, a group of persons united by ties of marriage and parenthood or adoption and consisting of a man, a woman, and their socially recognized children. This unit was once widely held to be the most basic and universal form of social organization. Anthropological research, however, has illuminated so much variability of this form that it is safer to assume that what is universal is a nuclear family complex in which the roles of husband, wife, mother, father, son, daughter, brother, and sister are embodied by people whose biological relationships do not necessarily conform to the Western definitions of these terms. In matrilineal societies, for example, a child may not be the responsibility of his biological genitor at all but of his mother's brother, whom he calls father. Closely related in form to the predominant nuclear-family unit are the conjugal family and the consanguineal family. As its name implies, the conjugal family is knit together primarily by the marriage tie and consists of mother, father, their children, and some close relatives. The consanguineal family, on the other hand, groups itself around a descent group or lineage whose members are said to be blood relatives (see descent; lineage) and consists of parents, their children, their children's children, and the children's spouses, who may belong consanguineally to another family. The stability of the conjugal family depends on the quality of the marriage of the husband and wife, and this relationship is more emphasized in industrialized, highly mobile societies in which people frequently must leave the residences of their blood relatives. In nonliterate societies, the perpetuation of the line has priority, and the consanguineal family derives its stability from its corporate nature and its permanence.