Kin Groups and Descent. Little information is recorded about the kin-based features of Sumu life. Conzemius (1932, 146) observed that the children of two brothers or of two sisters are considered real brothers and sisters and are not allowed to marry each other. The children of brothers and sisters, however, are not considered blood relatives, and union of such cousins is common.
Kinship Terminology. Some studies and dictionaries list certain Sumu kin terms, but apparently no study of their kinship terminology exists.