These genes partly overlap with those for several other traits, including openness to experience and risk-taking behavior. Social attitudes Prejudice Violence. These Y-linked proteins would not be recognized in the mother's immune system because she is female, causing her to develop antibodies which would travel through the placental barrier into the fetal compartment. LeVay also conducted some of these early researches. Nonetheless, it is possible to conclude that, given the difference in sexuality in so many sets of identical twins, sexual orientation cannot be attributed solely to genetic factors.
Jillian. Age: 29.
There are, however, different ways of living with homosexual desires.
Kara. Age: 22.
Biology and sexual orientation
One explanation for these differences is the idea that differential exposure to hormone levels in the womb during fetal development may change the masculinization of the brain in homosexual men. William Byne and colleagues attempted to identify the size differences reported in INAH 1—4 by replicating the experiment using brain sample from other subjects: 14 HIV-positive homosexual males, 34 presumed heterosexual males 10 HIV-positive , and 34 presumed heterosexual females 9 HIV-positive. The second group comprised 16 men whose sexual orientation was unknown, but whom the researchers presumed to be heterosexual.