Identity building is a complex process located at the crossover between the synchronic dimension of the subject, focussed on the present time (affiliation) and the diachronic dimension, that places the subject in a historical context (filiation). Over and beyond the vertical relationship to parents and to grandparents, one's identity is also built up via horizontal relationships. Brothers and sisters have joint, shared relationships while, at the same time, each sibling tends to differentiate him or herself from the others. Now, the migratory movement often means that the subject concerned will be liable to a foundering in the transmission process and a reshuffling of identification characteristics. This leads us to ask the following questions: how does the migratory process lead to changes in family relationships and, more especially, those amongst siblings? Can sibling relationships serve as supports for identity negotiation and integration of the migrant? If so, in what ways? This research, therefore, is focussed on the building up of the identity of young adult immigrants to Quebec. More specifically, we examine interests us are the issues and processes that go into identity building, linked with sibling relationships on the one hand, and with the migration process on the other. We have made use of a qualitative research process that has allowed us to interview seven adults (three interviews with each one) so as to explore with them the development of their family and sibling relationships along with their intercultural experience. The first stage in the analysis of the results is now complete and indicates that brothers and sisters may, at one and the same time, represent an emblem of continuity that can coexist with the uprooting effect of immigration; contribute to the building up of new affiliate links within the host society, and participate in the subject's renegotiation of his or her identity.