[Genetic evaluation of male homosexuality].

The family trees of 16 homosexual males are evaluated in the material of their Genetic Counselling Clinic. The familial cluster of three cases corresponded to the X-linked recessive inheritance. The results of family, twin and adoption studies are reviewed and the recent findings of molecular genetic and brain researches are summarised. Male homosexuality comprises of different subgroups, but one major entity is caused by X-linked recessive gene(s). This genetic background represent a predisposition which is triggered or suppressed by external factors.