Sexual BeliefsThe Rorapori believe that the embryo is solely the the product of the father's seed, and thus a child is only "genetically" related to his father's family. Marriages within the patrilineal family are considered incestuous within five degrees of separation. However, marriage to the child(ren) of one's father's sister or one's mother's siblings are not taboo.
If a Rorapori dies in a monogamous marriage, and the man's father is still alive, his, the deceased's, eldest brother, or his immediately younger brother if the deceased brother is the eldest, must marry the widow and raise the children. If the father is dead, the youngest brother then marries the widow, following Rorapori ultigeniture. This is the only circumstance under which polygynous marriage is permissible.
Polyandrous marriages are not uncommon, and their logic seems to derive from both a desire to hold wealth and inheritance within one generation, and to ensure no child is raised without a father. Polyandrous marriages are always fraternal, and arranged by the eldest brother in the union, with permission of his father and his elder brothers. The younger male partner(s) have no say. The younger husband(s) need not be of age, although they can be no more than twelve years younger than the eldest husband. If the younger husbands are not of age at the time of the marriage, they take altered form of their surname and have no rights to any children their wife bears during their, the younger husbands', minority.