Kin Groups and Descent. Siwai society is divided into many matrilineages, but most villages are primarily composed of two matrilineages whose members have been marrying each other for generations. Such intermarrying matrilineages become local descent groups. Most matrilineages produce their own stores of wealth and their own particular tracts of land. There is regular interaction between matrilineage members.
Kinship Terminology. Siwai kinship terminology is similar to other terminologies that have been labeled Dravidian, characterized as two-section systems, and associated with bilateral cross-cousin marriage and sister exchange. Genealogical knowledge is very shallow. There are few strictly affinal terms.