Kinship, Double unilineal descent

Double unilineal, or duolineal, descent is very rare. Arguably, a form of double descent exists among groups of Australian Aboriginals, but the most definitive examples are found in Africa. The Yako of Nigeria and the Herero of Namibia and Botswana are best known. The principle of double descent is that two kinds of descent group, patrilineal and matrilineal, exist