Neurologist and Co-Founder of the Institute of Gay and Lesbian Education
Pro to the question "Is Sexual Orientation Determined at Birth?"
"Although quite a few of the findings [on studies regarding the basis of sexual orientation] are inconsistent between studies or await independent replication, my general conclusion is that biological processes, especially the prenatal, hormonally-controlled sexual differentiation of the brain, are likely to influence a person’s ultimate sexual orientation."
"The Biology of Sexual Orientation," www.simonlevay.com, updated Apr. 2009