Sexual differentiation in humans development can only occur when the fetal testis secretes key hormones at a critical period in early gestation. The testes begin to secrete three hormones that influence the male internal and external genitalia: they secrete anti-müllerian hormone (AMH), testosterone, and dihydrotestosterone (DHT). Anti-müllerian hormone causes the paramesonephric ducts to regress. Testosterone converts the mesonephric ducts into male accessory structures, including the epididymis, vas deferens, and seminal vesicle. Testosterone will also control the descending of the testes from the abdomen into the scrotum. Many other genes found on other autosomes, including"WT-1", "SOX9", "SF-1" also play a role in gonadal development. Females:
Sexual Preference (book) that while Bell "et al."′s suggestion that biological factors have a stronger influence on exclusive homosexuality than they have on bisexuality may seem plausible, it has not been directly tested and appears to conflict with available evidence, such as that concerning prenatal hormone exposure. The psychologist Bruce Rind credited Bell "et al." with disproving psychoanalytic theories about the development of homosexuality, along with the idea that childhood seduction causes homosexuality. The psychologist Mark Yarhouse wrote that while "Sexual Preference" is cited by proponents of a biological explanation, it relies on retrospective memory recall, which can be unreliable. The psychologist J.