Breast development extension adrenocorticotropic hormone (ACTH)), and thyroid hormones such as thyroxine (and by extension thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH)) also play permissive but less well-understood/poorly-characterized roles in breast development during both puberty and pregnancy, and are required for full functional development. Leptin has also been found to be an important factor in mammary gland development, and has been found to promote mammary epithelial cell proliferation. In contrast to the female-associated sex hormones, estrogen and progesterone, the male-associated sex hormones, the androgens, such as testosterone and dihydrotestosterone (DHT), powerfully suppress the action of estrogen in the breasts. At least one
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.