From a link in a post by ingin in GD.
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=389x3722826Kinda interesting.
While most men prefer women as their sexual partners, some are bisexual and others are
homosexuals. It has been debated for a long time whether a person’s sexual preference is
innate, learned or due to a combination of both causes.
It was recently discovered that the
human right- versus left-hand-use preference and the direction of scalp hair-whorl rotation
develop from a common genetic mechanism (1). Such a mechanism controls functional
specialization of brain hemispheres. Whether the same mechanism specifying mental
makeup influences sexual preference was determined here by comparing the hair-whorl
rotation of groups enriched with homosexual men with that of males at large.
Only a minority of 8.2% (n = 207) unselected “control” group of males developed
counterclockwise rotation. In contrast, all three samples enriched with homosexual men
exhibited highly significant (P < 0.0001), 3.6-fold excess (29.8%, n = 272), counterclockwise
rotation. These results suggest that sexual preference may be influenced in a significant
proportion of homosexual men by a biological/genetic factor that also controls direction of
hair-whorl rotation.http://www.ias.ac.in/jgenet/Vol83No3/jgdec2004-jg639.pdf