Starting from the traditional aetiology of mental illness in Sub Saharan Africa, the author questions the concept of  » ancestor child  » in the interpretation of mental disorders with African adolescents belonging to the first generation of migrant adolescents. Starting from an ethnopsychoanalytic reading of two clinical vignettes, the author stresses the reintroduction of the symbolical function of the father, erected as it is on that very traditional etiology, with two families exposed to acculturation. The author evidences the therapeutic efficiency of that ethnopsychological method which enabled both these adolescents to substract themselves from the denial of a fialitation ascribed by such a cultural logic in order not to be sacrificed to such a  » status  » of an  » ancestor child « .