The "Bottoms-Up Gene"

Being a "sissy" is not limited to boyhood. Some adult gay men also are regarded as "swish," "camp," and effeminate, but we made no attempt to measure gender atypicality in adulthood because other research had shown that, in reality, it correlates quite poorly with sexual orientation. It also seemed intuitively obvious that this dimension of personality is too much influenced by the social and cultural environment to have any significant biological or genetic component.

There is, however, one aspect of adult gay male behavior that is notable and measurably gender atypical, and that is the sex act itself. The very fact of having sex with another man is and of itself gender atypical, and of the large number of different things a man can do sexually, the most gender atypical is to take the receptive role in anal intercourse.

Every subject in our study was questioned about preferred and performed sex acts. This was important not just to understand their sexuality, but also to learn about their risk for HIV infection, information we needed for the study of AIDS. Both the gay and straight participants were asked about the following sex acts: touching and masturbation, oral-genital, penile-vaginal, penile-anal, oral-anal, and "other." As appropriate, the subjects were asked whether they engaged in these activities insertively, receptively, or mutually. They also were asked what activities they would prefer to perform, or fantasied about, as compared to what they actually did. This was important to see if people had altered their behavior because of the risk of AIDS and other sexually transmitted diseases.

Among the heterosexual men we interviewed, the insertive role in penile-vaginal intercourse was by far the leading choice in fact and fantasy, and the range of other activities was limited. The gay men exhibited a more flexible and diverse repertoire of sexual activities and desires. Mutual oral-genital contact and masturbation were about tied for first place, penile-anal intercourse was next, and oral-anal and "other" were last. Only 16 percent of the men listed receptive anal intercourse as their preferred sexual activity, either in reality or in fantasy.

This information allowed us to test the hypothesis that the "gay gene" is actually a locus for receptive anal intercourse. Using the same strategy we used for the "sissy gene," we divided the 40 pairs of gay brothers into Xq28-concordant and Xq28-discordant groups and compared the number of men who listed receptive anal intercourse as their preferred sexual activity. There was no significant correlation of any sort, nor was there a difference among all gay men with gay brothers compared to those without gay brothers. In fact, there was little correlation at all between the sexual activities preferred and engaged in by gay brothers, indicating there is as yet no evidence that the particular sexual activity a person prefers is genetically influenced.

"The Science of Desire: The Search for the Gay Gene and the Biology of Behavior." 1994, Dean Hamer, Ph.D., Chief, Section on Gene Structure and Regulation, National Cancer Institute in Bethesda, Maryland.
Special thanks to Tim Robbins for contributing this piece.