Tswana patrilineal customs predominate through the court systems, though kin groups are organized according to patrilineal, matrilineal, double-descent, or bilateral principles depending on the ethnic group. Some groups have named clans, others have more fluid boundaries. Kin groups larger than the household or compound group may cooperate for a healing or strengthening ritual invoking ancestors, and should participate in funerals, which are significant events for defining relationships and obligations.