Basic Concepts

Broadly, a family is a group of persons directly linked by connections, the adult members of which assume responsibility for caring for children. Kinship ties are connections between individuals, established either through marriage or through the lines of descent that connect blood relatives (mothers, fathers, siblings, offspring, etc.). Marriage may be defined as a socially acknowledged and approved sexual union between two adult individuals. When two people marry, they become kin one another; the marriage bond also, however, connects together a wider range of kinspeople. Parents, sisters, brothers and other blood relatives become relatives of the partner through marriage.

Family relationships are often recognized within wider kinship groups. In virtually all societies we can identify what sociologists and anthropologists call the nuclear family, two adults living together in a household with their own or adopted children. In most traditional societies, the nuclear family was part of a larger kinship network of some type. When close relatives other than a married couple and children live either in the same household or in a close and continuous relationship with one another, we speak of an extended family. An extended family may include grandparents, sisters and their husbands, brothers and their wives, aunts and nephews.

Patterns of Marriage

Cultural norms, and often laws, identify people as suitable or unsuitable marriage partners. Some marital norms promote endogamy, marriage between people of the same social category. Endogamy limits marriage prospects to others of the same age, race, religion, or social class. By contrast, exogamy mandates marriage between people of different social categories. In rural areas of India, for example, people are expected to marry someone of the same caste (endogamy) but from a different village (exogamy). On the one hand, the logic of endogamy is that people of similar position pass along their standing to their offspring, thereby maintaining the traditional social hierarchy. Exogamy, on the other, builds alliances and encourages cultural diffusion.

In high-income nations, laws prescribe monogamy (from the Greek, meaning “one union”), marriage that unites two partners. Whereas monogamy is the rule in high-income countries, many lower-income countries – especially in Africa and southern Asia – permit polygamy (from the Greek, meaning “many unions”), marriage that unites three or more people. Polygamy takes two forms: (a) polygyny and (b) polyandry. By far the more common form is polygyny (from the Greek, meaning “many women”), marriage that unites one man and two or more women. For example, Islamic nations in the Middle East and Africa permit men to four wives. Even so, most Islamic families are monogamous because a very few men can afford to support several wives and even more children. Polyandry (from the Greek, meaning “many men” or “many husbands”) is marriage that unites one woman and two or more men. One case of this rare pattern is seen is Tibet, a mountainous land where agriculture is difficult. There, polyandry discourages the division of land into parcels too small to support a family and divides the work of farming among many men.