Complex sentence: There is no substantive evidence which suggests parenting or early childhood experiences play a role when it comes to sexual orientation; when it comes to same-sex sexual behavior, shared or familial environment plays no role for men and minor role for women.
Split into simpler sentences: There is no substantive evidence which suggests parenting or early childhood experiences play a role when it comes to sexual orientation. With regard to same-sex sexual behavior, shared or familial environment plays no role for men and minor role for women.