Even the boundary between kin and non-kin is not clearly marked. Though they recognised no kin tie, they were constantly together. This case was perhaps exceptional, but it illustrates a perfectly acceptable type of relationship. The Nuer, a patrilineal people of the southern Sudan, cannot imagine a confusion of distinct kinship roles. In particular, the distinction between agnates and other consanguineal kin and affines is sharp.
Most unilineal societies have such sharp distinctions.
In these villages, on the contrary, again with one major exception, father's sister's daughter, different kinds of uncles and aunts are not theoretically sharply distinct. A man may through the practice of marriage, be mother's brother and classificatory father's brother to the same child. Some informants even denied, incorrectly, that the roles of mother's brother and father's brother differ at all. The lack of specificity in kinship roles goes with an absence of formal or organised sanctions. Those who feel that they have been let down have no sanctions to apply except to withdraw from social relations with the offenders - unless the matter is serious enough to call for violence.