Marriage. Yanomamö marriage rules are prescriptive in that marital partners must be cross cousins. Ideally, mates are double cross cousins, a result of the practice of sister exchange. Women typically marry soon after their first menses with men in their early twenties. Although marriage is patrilocal, a husband must live with his parents-inlaw for several years and perform bride-service. This rule may be relaxed for high-status males. Polygyny is permitted and 10 to 20 percent of all males at any time are polygynists. Ideally, polygyny is sororal, and levirate and sororate are practiced. Men and women average 2.8 marital partners during their lifetime, with about 75 percent of those marriages ending as a result of divorce and the balance as a result of death of one of the partners.
Domestic Unit. Monogamous or polygynous nuclear families are the rule among the Yanomamö. Deviations from this pattern occur when aged parents live closely associated with married children or when newlyweds dwell with one or the other's parents.
Inheritance. Neither status or property is inherited among the Yanomamö. At death, kin incinerate the personal property of the deceased.
Socialization. Mothers dominate in the care of infants, who spend most of their time suspended in a simple sling that runs diagonally from the caretaker's right shoulder to just above the left hip. During this time the mother carries her infant to forest and garden as she works. While the child is being weaned it is more frequently cared for by older sisters and female relatives. Weaning from the breast and the sling may occur abruptly, especially if the mother is pregnant, and is occasioned by howls of protest by the child. Although fathers will affectionately play with infants, they spend very little time (less than five minutes per day) in care-giving activities. In contrast to boys, girls begin making important economic contributions by the age of 6 as they accompany mothers in gardening and gathering excursions and assist in food preparation. Boys spend most of their time playing rough-and-tumble games, shooting toy bows, and roaming in the nearby forest in same-sex groups. Parents encourage sons and daughters to be assertive and to respond to insults with physical or verbal aggression. Physical punishment (slapping, punching, or striking with objects) is not uncommon. The girl's puberty ceremony ( yobomou ) begins immediately during her first menses. During this time a girl is secluded for a few weeks in a small shelter near her parent's hearth and is restricted to a special diet; her head is shaved upon departure.