Cultural recognition of children as kin of one or both parents is basis for the descent concept. Some societies trace through both parents (e.g., Canada and the United States). Other societies trace descent through only one of the parent’s family line.
There are two basic descent systems: corporate and cognatic.
Cognatic descent is also referred to as non-unilineal descent and there are two types of cognatic descent: bilateral and ambilineal.
Anthropological data suggests that cognatic descent arose in cultures where warfare is uncommon and there is a political organization that can organize and fight on behalf of the members.
In bilateral systems, children are equally descended through both parents. People from both sides of the family are considered relatives. This is the form of descent practiced in the United States.
Ambilineal systems require children to choose either the mother or father’s side of the family to be reckoned relatives. Some Native American tribes use the ambilineal system. In the illustration below, if EGO chooses the father’s side of the family, then everyone marked in blue would be considered kin. If EGO chooses the mother’s side, then everyone marked in orange would be considered family.
In corporate descent cultures only one family line is recognized as kin. The group typically owns property together.
When family is reckoned along the father’s line the group is patrilineal.
When family is reckoned along the mother’s line the group is matrilineal.