The kinship system proper to the Damgan society in southern Brittany is based on the “brother/sister”, “husband/wife”, “uncle/brother-in-law” and “father-in-law/uncle” assymmetries. Kinship includes the bond of consanguinity and, by extension, of affinity. When both change they directly affect the bonds of kinship. Until the middle of the fifties the permanence of social unity was ensured by couples that lived on the same ground from generation to generation and were bonded by the renewal of “wheat lineages” and by the cult of the dead. This article is based both on materials collected since 1991 during successive field works and on a many years’ anthropological reflection on consanguinity and affinity.