These possible biological factors are: genetics, prenatal hormones, differing brain structure etc. In America homosexuality is only about 3-4% and in women 1-2%; as members of a minority they often struggle with their sexual orientation/lifestyle. In homosexual men, the size of their anterior hypothalamus is smaller, and the anterior commissure is larger, that is why scientist believes differing brain structure could be a possible factor. Homosexual men’s hypothalamus reacts to the smell of sex-related hormones, just as a woman’s does. Another physiological difference is that homosexual men and heterosexual women have, on average, equally proportioned brain hemispheres. Homosexual women and heterosexual men have, on average, slightly larger right brain