[Populations and heredity: at an intersection]

A population can be defined using different criteria, for example criteria of a geographical or medical nature. Researchers, or even patients and journalists, have complementary or contradictory views of this notion. Heredity is not only a biological fact; it is also a social fact. A systematic study of the genealogical corpus of a group of patients makes it possible to evaluate the soundness of the phenotypic criterion used to define a subpopulation that shares a common pathological heredity.