Born that gay

Do recent neurological studies prove once and for all that homosexuality is biological?

By Robert Burton

Read more: Homosexuality, Genetics, Neurology, Robert Burton, Brains, Mind Reader, Environment & Science

Sept. 12, 2008 | As the accuracy and resolution of brain imaging improve, we can expect virtually all behavior to be shown to be associated with demonstrable brain changes. It shouldn't come as a surprise that imaging studies of sexual orientation are increasingly revealing anatomic and functional differences between "straight" and "gay" brains. But demonstrating such changes doesn't answer the age-old question of how much our sexual preferences are innate and how much they are fueled by environmental exposure, cultural norms and conscious personal choices.

One way to distinguish the effects of nature from nurture would be to look at brain regions believed by neuro-anatomists to be fully formed at birth and impervious to subsequent environmental effects, both physical and psychological. Focusing on such brain regions, a research team at the Karolinska Institute in Stockholm, Sweden, headed by neuroscientist Ivanka Savic, obtained MRIs for 90 adult volunteers -- 25 straight men, 25 straight women, 20 gay men and 20 lesbians. Using the latest quantitative techniques for assessing cerebral symmetry and functional connections between various areas of brain, Savic was able to demonstrate highly statistically significant differences between straight and gay brains. Gay and lesbian brains more closely resembled the brains of straight volunteers of the opposite sex than the brains of heterosexual members of the same sex.

In their study, reported in the June 16, 2008, issue of the Proceedings of the National Academy of Sciences, Savic said, "This is the most robust measure so far of cerebral differences between homosexual and heterosexual subjects." Although Savic admits that her study cannot distinguish between genetic or prenatal intrauterine environmental changes, such as relative differences in sex hormone levels, her studies do suggest that our sexual preferences are, at least in large part, determined by the time of birth.

Not long after reading the study, I got a call from neurologist Jerome Goldstein, M.D., 67, once a fellow resident in the UCSF neurology training program. This fall, Goldstein, an internationally respected headache researcher and sometimes controversial gay activist, is giving a series of lectures on the innate biology of gayness. He was phoning to ask if I had seen the study and if I might write about the latest scientific evidence supporting the biology of gayness. I decided to interview him instead. Goldstein is compact, rapid-talking and constantly on the verge of impatience. Yet during our conversations he was subdued, confessional in tone, with frequent pauses to gather his thoughts; the seriousness of his concerns was palpable.

Jerry, you've been an outspoken gay activist for 40-plus years. Why the sudden interest in the biology of sexual orientation?

I was aware that I was attracted to men by age 8, even though I did not have any gay sexual experiences until I was 19. Meanwhile, despite having no sex or even a clear understanding of what homosexuality meant, virtually everyone that I encountered, including my dear parents, made a point of telling me that homosexuality was dirty, sinful and a phase that would pass.

Beginning my sophomore year in college, and before my first gay experience, I began the endless rounds of psychiatrists and counselors. I even tried to modify my behavior to make it acceptable. Sadly, even though I now know better, and am fully aware of the overwhelming evidence as to the underlying neurobiologic predisposition to gayness, I have never been able to entirely shake this feeling of guilt and wrongdoing. Future generations should be spared. Right now, I'm interested in seeing that good science prevails over outdated, misguided psychology and false-headed thinking that homosexuality is a conscious choice.

Do you think people accept that homosexuality arises out of biological predispositions?

Only on the surface. Down deep, there's a lingering suspicion that, even if the cause is biological, there is something intrinsically wrong with being gay. It has been 35 years since homosexuality was removed from a psychiatric diagnostic category and we [still] don't see the changes in the way people think. Sadly, even our major neurological societies haven't taken a serious look at the biology of sexual orientation. For example, when was the last time that you saw the American Academy of Neurology even address the subject? And the general public? Just listen to right-wing talk show hosts offering to pray for my sins. Or look at the damage caused by the religious right and its "conversion therapy," which attempts to alter an inborn characteristic of human behavior. I don't want pity and sympathy, I want scientific understanding based on logic and reason.

Could you give me a brief rundown of what you think is the most compelling evidence supporting the biology of gayness?

Keep in mind that sexual orientation is exceedingly complex and not reducible to a single gene or hormonal aberration, or explained by demonstrable anatomic brain differences. But by examining multiple lines of evidence, you can begin to connect the dots as to how biology influences sexual preferences. With these caveats in mind, let's look at the history leading up to the present functional imaging studies.

In 1991, Simon LeVay, formerly a professor of neuroscience at Harvard and the Salk Biological Institute, claimed to have discovered specific anatomic differences between gay and straight brains, primarily in a region of the hypothalamus believed to have a major influence on sexual behavior. By the way, this region's fetal development is greatly influenced by the levels of intrauterine testosterone, a major reason why intrauterine shifts of sex hormone levels are thought by some researchers to contribute to sexual preference.

But LeVay's work was considered controversial, nonreproducible, and part of a gay political agenda. The real take-away was the promise that neuroscience might one day offer better insights into the origins of homosexuality.

At the same time, there were a variety of quasi-scientific studies claiming to uncover markers for "gay tendencies." One suggested that you could tell whether or not you're gay by whether your hair whorl -- that patch of hair on the crown of your head -- curled clockwise or counterclockwise. Another suggested that you could tell by the relative symmetry of your second and fourth digits. Those studies weren't exactly good science and certainly didn't make the biology of sexual orientation an attractive area for basic research funding.

Next page: Are you equating homosexuality with a taste for Brussels sprouts?