Anti-mullerian hormone receptor type 2 Anti-mullerian hormone receptor type 2 Anti-Mullerian hormone receptor type 2 is a protein that in humans is encoded by the AMHR2 gene. This gene encodes the receptor for the anti-Mullerian hormone (AMH) which, in addition to testosterone, results in male sex differentiation. AMH and testosterone are produced in the testes by different cells and have different effects. Testosterone promotes the development of male genitalia while the binding of AMH to the encoded receptor prevents the development of the mullerian ducts into uterus and Fallopian tubes. Mutations in this gene are associated with persistent Mullerian duct syndrome type II. Alternatively spliced
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