Biological differences in gay men and lesbians
Some studies have found correlations between physiology of people and their sexuality.
These studies provide evidence which they claim suggests that:
* Gay men report, on an average, slightly longer and thicker penises than non-gay men.
* Gay men and straight women have, on average, equally proportioned brain hemispheres. Lesbian women and straight men have, on average, slightly larger right brain hemispheres.
* The VIP SCN nucleus of the hypothalamus is larger in men than in women, and larger in gay men than in heterosexual men.
* The average size of the INAH-3 in the brains of gay men is approximately the same size as INAH 3 in women, which is significantly smaller, and the cells more densely packed, than in heterosexual men's brains.
* The anterior commissure is larger in women than men and was reported to be larger in gay men than in non-gay men, but a subsequent study found no such difference.
* Gay men's brains respond differently to fluoxetine, a selective serotonin reuptake inhibitor.
* The functioning of the inner ear and the central auditory system in lesbians and bisexual women are more like the functional properties found in men than in non-gay women (the researchers argued this finding was consistent with the prenatal hormonal theory of sexual orientation).
* The suprachiasmatic nucleus was found by Swaab and Hopffman to be larger in gay men than in non-gay men, the suprachiasmatic nucleus is also known to be larger in men than in women.
* The startle response (eyeblink following a loud sound) is similarly masculinized in lesbians and bisexual women.
* Gay and non-gay people's brains respond differently to two putative sex pheromones (AND, found in male armpit secretions, and EST, found in female urine).
* The amygdala, a region of the brain, is more active in gay men than non-gay men when exposed to sexually arousing material.
* Finger length ratios between the index and ring fingers may be different between non-gay and lesbian women.
* Gay men and lesbians are significantly more likely to be left-handed or ambidextrous than non-gay men and women; Simon LeVay argues that because "[h]and preference is observable before birth... [t]he observation of increased non-right-handness in gay people is therefore consistent with the idea that sexual orientation is influenced by prenatal processes," perhaps heredity.
* A study of 50 gay men found 23% had counterclockwise hair whirl, as opposed to 8% in the general population. This may correlate with left-handedness.
* Gay men have increased ridge density in the fingerprints on their left thumbs and pinkies.
* Length of limbs and hands of gay men is smaller compared to height than the general population, but only among white men.
http://en.wikipedia.org/wiki/Biology_an ... rientation