The literature on ethnically “mixed” families generally focuses on the experiences of couples but rarely on those of their children. Some studies on these young people reveal their various forms of identity and the way the society in which they live and where they grow up affect their self-identification, highlighting the structuring power of context on the identity formation of children of mixed families. To nuance the understanding of this identity construction and to comprehend the becoming of children of mixed families, this article investigates their ethnic identification and proposes a case study of individuals from Filipino-Belgian and Thai-Belgian families in Belgium. The empirical data collected notably in this country show that these persons define themselves in different ways. Most of them present themselves variably depending on the place (circumscribed geographical and sociocultural space) where they are, on their interlocutors (interpersonal situation) and on the moment in time (temporality), revealing the structuring power of context on their ethnic identification. Other interviewed persons identify themselves on a stable basis, which demonstrates their resistance to biographical challenges and suggests that ethnic self-identification is not always fluid or fluctuating.