In the context of human society, a family (from familia) is a group of people affiliated either by consanguinity (by recognized birth), affinity (by marriage or other relationship), or co-residence (as implied by the etymology of the English word "family") or some combination of these. Members of the immediate family may include spouses, parents, brothers, sisters, sons, and daughters. Members of the extended family may include grandparents, aunts, uncles, cousins, nephews, nieces, and siblings-in-law. Sometimes these are also considered members of the immediate family, depending on an individual's specific relationship with them.In most societies, the family is the principal institution for the socialization of children. As the basic unit for raising children, anthropologists generally classify most family organizations as matrifocal (a mother and her children); conjugal (a wife, her husband, and children, also called the nuclear family); avuncular (for example, a grandparent, a brother, his sister, and her children); or extended (parents and children co-reside with other members of one parent's family). Sexual relations among the members are regulated by rules concerning incest such as the incest taboo.