Lewis Henry Morgan published Systems of Consanguinity and Affinity of the Human Family in 1871. This work became a foundational text for anthropologists studying social relationships across cultures.
Lewis Henry Morgan identified six major patterns of kinship systems including Iroquois, Crow, Omaha, Eskimo, Hawaiian, and Sudanese types. Dravidian kinship emerged later as a distinct classical type of classificatory system.
The Yakurr people of Nigeria affiliate individuals equally with relatives from both father's and mother's sides through a bilateral system. This bilateral system contrasts sharply with unilineal rules found elsewhere such as patrilineal or matrilineal systems.
David M. Schneider published American kinship: a cultural account in 1968 challenging core assumptions because he concluded that anthropologists mistakenly assumed their own cultural values were universal for all human cultures. His critique suggested the entire enterprise of kinship might be built on faulty foundations regarding blood ties and natural marriage.
Nurture kinship highlights how relationships may be brought into being through acts of giving and receiving care rather than genetic relatedness. Scholars argue these social bonds are mediated by shared living contexts instead of pure biology or genealogical connections.