In Western culture, a family is defined specifically as a group of people affiliated by blood or by legal ties such as marriage or adoption. Many anthropologists argue that the notion of "blood" must be understood metaphorically; some argue that there are many non-Western societies where family is understood through other concepts rather than "blood."

Family cross-culturally

According to sociology and anthropology, the primary function of the family is to reproduce society, either biologically, socially, or both. Thus, one's experience of one's family shifts over time. From the perspective of children, the family is a family of orientation: the family serves to locate children socially, and plays a major role in their enculturation and socialization. From the point of view of the parent(s), the family is a family of procreation the goal of which is to produce and enculturate and socialize children. However, producing children is not the only function of the family. In societies with a sexual division of labor, marriage, and the resulting relationship between a husband and wife, is necessary for the formation of an economically productive household. In modern societies marriage entails particular rights and privilege that encourage the formation of new families even when there is no intention of having children.

The structure of families traditionally hinges on relations between parents and children, between spouses, or both. Consequently, there are three major types of family: matrifocal, consanguineal, and conjugal. (Note: these are ideal families. In all societies there are acceptable deviations from the ideal or statistical norm, owing either to incidental circumstances, such as the death of a member of the family or infertility, or personal preferences).

A matrifocal family consists of a mother and her children. Generally, these children are her biological offspring, although adoption of children is a practice in nearly every society. This kind of family is common where women have the resources to rear their children by themselves, or where men are more mobile than women.

A consanguineal family consists of a mother and her children, and other people -- usually the family of the mother. This kind of family is common where mothers do not have the resources to rear their children on their own, and especially where property is inherited. When important property is owned by men, consanguineal families commonly consist of a husband and wife, their children, and other members of the husband's family.

A conjugal family consists of one or more mothers and their children, and/or one or more spouses (usually husbands). This kind of family is common where men desire to assert control over children, or where there is a sexual division of labor requiring the participation of both men and women, and where families are relatively mobile.