Kin Groups and Descent. There are two significant corporate groups in a Motu village: the household, comprising one or more nuclear families; and the iduhu, comprising a number of households located together in their own residential section of the village. Nuclear families within a Household, and households within an iduhu, are usually linked by agnatic ties: between fathers, sons, and brothers in a Household, and between agnatic descendants of its founder in an iduhu. Some rights (e.g., to share in an iduhu's fishing catch) extend also to sisters and their children, and some (e.g., to land) extend to further descendants bilaterally, but the core members of the iduhu with the strongest claims to its scarce material and ritual resources are agnates. Females marry out, but subsequently retain close bonds with their fathers and brothers.
Kinship Terminology. With one complication, Motu Kinship terminology is of the so-called "Hawaiian" type, distinguishing cognates of one's own generation only by age ( kaka, older; tadi, younger) or sex ( taihu, opposite sex) and applying only one term ( tubu ) to all cognates of one's grandparents' or grandchildren's generation. The complication occurs in the terms used by proximate generations: In the generation of one's parents, mother's male cognates and husbands of Father's female cognates (both called vava ) and father's female cognates and the wives of mother's male cognates ( lala ) are distinguished from father and his male cognates (tama) and mother and her female cognates ( sina ), and these distinctions operate reciprocally for cognates of one's children's Generation. This type of terminology, sometimes called bifurcate-merging, is associated with classificatory brother-sister exchange marriage, which was traditionally not uncommon among the Motu.