Relationships between people which follow upon descent from a common ancestor. In every human society common descent (consanguinity) is thought to mark off a special category of kin, relationships with whom are different in kind from relationships with non-kin. Further significant distinctions may be made between relatives traced through the father and through the mother, between closer and more distant kin, and between kin of different generations. In small-scale, non-industrial societies, kinship relationships may provide the primary basis for association. Systems vary considerably in terms of residence patterns, marriage laws, and inheritance.