Kin Groups and Descent. At the core of Nyinba kinship is the concept of ru —literally, "bone"—which describes hereditary substance transmission through men and provides the basis for a system of patrilineal clanship. Clan Membership is important principally for marking social ranks within the community and for guiding marital choice through rules of exogamy. It has no economic and virtually no religious dimensions and does not generate any effective corporate groups. Although patrilineal descent appears important in several ethnic Tibetan societies in Nepal, it had minimal significance among agriculturalists in Tibet proper. Nyinba maintain that women transmit ru to their offspring through the medium of blood; these blood relationships provide a complementary, or matrifiliative, link to the mother's clan.
Kinship Terminology. The system of kin classification incorporates Omaha-type skewing rules, classifies relatives via same- and opposite-sex sibling links differently, and features spouse-equation rules that accord with a system of cross-cousin marriage. It also includes special terms that distinguish parents by relative age in complex, multipartner polyandrous and polygynous marriages.