The main aim of this article is to identify the essential features of the family, ascertain its specific nature and establish the boundaries between what is considered family and what is not, above all by distinguishing the family from the other primary groups. The phenomenon of pluralization of lifestyles has brought with it a strong degree of ambivalence. On one hand it seems to operate as a dedifferentiation process among primary relationships, as it emphasizes spontaneous feelings, values, roles and relationships of pure friendship and intimacy, while on the other hand it leads to the emergence of new distinctions between primary relationships, given that they are not all alike and cannot be categorised into homogenous groups. Therefore, in order to observe the family it is indispensable first of all to identify the network of links between the different individuals living in and around a family using a relational approach which highlights that the latent identity of the family consists of being a specific social relationship, sui generis, which emerges from the combined interweaving of four linked elements or components: gift, reciprocity, generativity and sexuality. Identifying the two ties in relationships between sexes and generations which constitute a family relationship makes it possible to simplify the wide variety of family forms which are currently taking shape in the social spectrum and aspire to be recognised officially: only the presence of at least one of the two relationships implies the existence of a family.