Androgen receptor the development and maintenance of the male sexual phenotype. In some cell types, testosterone interacts directly with androgen receptors, whereas, in others, testosterone is converted by 5-alpha-reductase to dihydrotestosterone, an even more potent agonist for androgen receptor activation. Testosterone appears to be the primary androgen receptor-activating hormone in the Wolffian duct, whereas dihydrotestosterone is the main androgenic hormone in the urogenital sinus, urogenital tubercle, and hair follicles. Hence, testosterone is responsible primarily for the development of male primary sexual characteristics, whereas dihydrotestosterone is responsible for secondary male characteristics. Androgens cause slow epiphysis, or maturation of the bones, but more of
Fraternal birth order and male sexual orientation not non-biological older brothers predicted sexual orientation in men. Further, if rearing or social factors underlie the fraternal birth order effect, then the amount of time reared with older brothers, either biological or non-biological, should predict sexual orientation because rearing time determines the relative opportunity that older brothers have to affect their younger sibling's (postnatal) sociosexual development. If a prenatal factor underlies the fraternal birth order effect, then a postnatal factor such as rearing time with older siblings (be they biological or non-biological) should have no impact on the sexual orientation of younger male siblings. The study found that the