Study: Lesbian
brains react differently to sex hormones

Swedish researchers are reporting in the current edition of Proceedings of the National Academy of Sciences that they've determined lesbians' brains react differently to sex hormones than do the brains of heterosexual women. This puts the brains of lesbians more in line with the way the brains of heterosexual men react to the pheromones, the Associated Press reports. Previous studies have shown that gay men's brains responded to pheromones similarly to the way heterosexual women's brains responded.

Researchers say the findings of all the studies give much more weight to the theory that sexual orientation is innate and not a response to environmental factors.

"It shows sexual orientation may very well have a different basis between men and women...this is not just a mirror image situation," Sandra Witelson, a Canadian expert on brain anatomy and sexual orientation, told the Associated Press. "The important thing is to be open to the likely situation that there are biological factors that contribute to sexual orientation."

The Swedish study had male and female study subjects sniff both male and female pheromones, which can trigger sexual responses. The researchers found that heterosexual men and lesbian women preferred the female pheromones to male pheromones. Heterosexual men and lesbian women also found the male hormone to be more irritating than the female one.

Brain scans also showed that female pheromones stimulated a response in the hypothalamus region of the brains of the male study subjects, a part of the brain linked with sexual response. Among heterosexual women, it was the male pheromones that created the sexual response. Brain scans of lesbians, however, showed that neither male nor female pheromones produced a response in the hypothalamus portion of the brain.

Gay men were not included in the study. However, the same research team reported last year that gay men's brains responded more positively to male pheromones than female sex chemicals. (The Advocate)