Man labioscrotal folds into the scrotum. Another significant hormone in sexual differentiation is the anti-Müllerian hormone, which inhibits development of the Müllerian ducts. In general, men suffer from many of the same illnesses as women. In comparison to women, men suffer from slightly more illnesses. Male life expectancy is slightly lower than female life expectancy, although the difference has narrowed in recent years. For males during puberty, testosterone, along with gonadotropins released by the pituitary gland, stimulates spermatogenesis, along with the full sexual distinction of a human male from a human female, while women are acted upon by estrogens and progesterone
Fraternal birth order and male sexual orientation sexual orientation via the fraternal birth order effect (for example, homosexual men with no older brothers) owe their homosexuality to other causes such as certain polymorphic genes (colloquially called "gay genes") or prenatal hormone levels during fetal development. Both direct and indirect evidence have demonstrated that the mechanism by which the fraternal birth order effect operates is prenatal in timing and biological in nature, rather than postnatal in timing or psychosocial in nature. Indirect evidence was found first when it was discovered that the fraternal birth order effect interacts with birth weight. Then, Bogaert (2006) produced direct evidence that the