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 support a prenatal origin to sexual orientation development in men and indicate that the fraternal birth order effect is probably the result of the mother's body's “memory” for both male births as well as male gestations (i.e., every instance of being pregnant with a male fetus). So even if a male fetus was not carried to term, he still increases the likelihood of homosexuality in any subsequent male fetuses gestated by the same mother. The existence of the fraternal birth order effect on male sexual orientation has been confirmed many times. One approach for establishing the ubiquity of this effect