Hormones impact both male and female brains. Different hormonal levels can result in female brains in male bodies and vice versa. Much of one’s sexual makeup relates to the hypothalamus where neurons that are involved in gender-specific sexual behavior are located. (Quartz, Steven R., PhD, and Terrence J. Sejnowski, PhD. Liars, Lovers, and Heroes. p 164-165. NY: HarperCollins Publishers Inc., 2002.)

The hormone DHEA is released during sexual activity. It can help to strengthen the immune system, build bones, and improve cognition. (Pease, Barbara and Allan. Why Men Don’t Listen and Women Can’t Read Maps. p 198-200. NY: Broadway Books, 1998.)

Sexual preferences are partly determined by hormones before birth. Typically there are higher numbers of male homosexuals over lesbians (e.g., more opportunities for something to “go wrong” in the process of converting the standard female embryo into a sexually competent male). (Wilson, Glenn. The Great Sex Divide. p 80-81. England: Peter Owen Publishers, 1989.)

Variations in androgens (male sex hormones) and estrogens (female sex hormones) can affect both body asymmetry and the degree/direction of gender differentiation in the brain. Provides examples. (Howard, Pierce J., PhD. The Owner’s Manual for the Brain. p 215-221. GA: Bard Press, 1994, 2000.)

There is an endocrine basis for homosexual preference if fetal development is interrupted and mother’s androgens are interfered with at the time of sexual differentiation in the brain. (Joy, Donald, PhD. The Innate Differences Between Males & Females (Audio Cassette). CO: Focus on the Family, 1967.)

Sex hormones create masculinization over time, so males can be more or less masculine. Females can be masculinized but not defeminized. (Durden-Smith, Jo, and Diane deSimone. Sex and the Brain. p 104-117. NY:Arbor House Publishing, 1983.