Marriage. Sororal polygyny is frequent, although most marriages are monogamous. Unions are generally stable. There is a preference for marriage with the daughter of the koka , a term applied to a kin category that includes, among others, the mother's brother and the sister's son.
Domestic Unit. Each elementary family has an open square room inside the hut to sleep, cook, and store some objects and horticultural products that are ready to be prepared. If two or more women have the same husband, they do not occupy contiguous rooms. Each married woman has a portion of the garden. The composition of the distinct domestic groups is not uniform. Perhaps the nucleus of a domestic group would be a man, his wife (or wives), his wife's brother (younger than him), and the latter's wife (or wives). Changes over time lead to very different compositions of the domestic group—for example, a married man and his married sons or a married man and his sister' s married sons.
Socialization. Infants and children are raised by their parents, helped by the other members of the domestic group. The Marubo do not use physical punishment in child rearing, but mothers menace or even treat their disobedient children with a species of cultivated stinging nettle, to which are attributed powers of liveliness and good luck in hunting. Children spend a large amount of time playing with their hut companions, especially their brothers and daughters by the same mother. Depending on their age and physical capacity, they can help the adults in their work.