Among the Aït Khebbach (south-eastern Morocco), filiation is patrilineal. But a thorough examination of kinship representations nuances this determinism. Indeed, during the first rituals of birth, which closely depend on women’s know-how (infant and mother caring, food prescriptions, breast-feeding practices, etc.) frequent references to uterine kinship are often noted. Some time after delivery interference of men in the mother-child couple can be lived as a threat: they are said to have the power of acting on lactation. This power enables them to reappropriate their descent, according to the system of agnatic kinship.