Kin Groups and Descent. The basic kin unit is the nuclear family, but it is often augmented by the addition of other kin, such as a widowed parent. Two or more married brothers, or a man and his wife and their married son, may sometimes reside in the same house, giving rise to an extended family. Descent is entirely bilateral. Even claims to the headmanship can be asserted equally through one's father or one's mother.
Kinship Terminology. Kuikuru kinship terms are basically Iroquoian, except that brother and sister terms have been extended to include not only parallel cousins but cross cousins as well, making the nomenclature Hawaiian for Ego's generation. Vestigial cross-cousin terms exist, though, indicating that at one time the terminology was consistently Iroquoian.