Kinship

Cultures use different kinship systems and rules to define and describe relationships between members of a cultural or familial group.

Throughout the years, anthropologists have created kinship diagrams, which are systems that define kinship rules and terms. If you've ever wondered who your second or third cousin is, these are the types of terms that kinship diagrams define. What you call different family members and your relationship to them varies culturally. For example, in Spanish, there are two different words for cousin—one feminine, one masculine. However, in English we don't differentiate between words for cousins, and instead there is just one.

Descent

Descent is one of the key concepts in kinship systems. Descent describes the rules and ideas about ancestry and where or who an individual is descended from.

Bilateral descent is a less-common form of descent, where the individual is equally affiliated with both the mother and the father's side of the family.

In contrast, most societies practice unilineal descent. In unilineal descent, ancestry is usually mainly affiliated with one side of the family. When an individual is affiliated with the mother's side of the family, descent is said to be matrilineal. However, if an individual is affiliated with the father's side of the family, descent is said to be patrilineal. Patrilineal descent is the most common type of descent in the world. A good example of this is the tradition in North America of a wife taking her husband's last name, instead of her own.

However, these are all just general categories. In many cultures, rules of descent can be more complicated, and can refer to both sides of the family at various occasions.

Descent rules are important for many cultures, because it can end up determining—at least partially—where individuals can live, what they inherit, and even who they can marry.

Exogamy and endogamy

In terms of marriage, exogamy and endogamy are two main types of rules that describe who an individual can marry. In some cultures, an individual can marry virtually whomever they want, as long as it doesn't break any social taboos. In others, rules are more prescriptive.

For example, exogamy occurs when an individual has to marry outside of their social group. This particularly occurs in cultures with clans, where society is sub-divided into smaller groups. Linguistic exogamy is an uncommon type of marriage rule where an individual must marry someone who speaks a different language than they do.

In contrast, endogamy is a marriage rule where a person must marry within their social group. For example, this could involve an individual marrying someone who is the same social class as they are.

Household rules

Besides marriage and descent, many cultures often have rules about who makes up a household. These rules can either be specific and strict, or more general guidelines about cultural norms.

After marriage, depending on cultural norms, a new couple can choose to live with either partner's parents (matrilocality or patrilocality), or can choose to create a new household (neolocality). Neolocal residence is a common practice in much of both North America and Europe today, but all residency types are practiced.