November 21, 2003

University study links neurochemistry to sexual orientation in homosexual, heterosexual men

A study recently released by researchers at the University indicates linkages between neurochemistry and sexual orientation in exclusively homosexual and heterosexual men.

The study proves the existence of a physiological basis for sexual preference. It verifies the claim that one's sexual orientation is not a matter of choice, but rather is dictated by inborn chemical factors.

Department of Biopsychology Professor Emeritus Howard Moltz, who authored the study, said the goal in his research was to determine whether there was any connection between brain activity and sexual preference. "We thought that exclusive homosexuality may be hardwired and not a matter of choice as such," he said.

Moltz interviewed 80 homosexual men for the study, from which he chose eight as "exclusive." Moltz said that, unlike most gay men, these "exclusives" have never felt aroused by females. Moltz also chose eight exclusively heterosexual men, who had never been attracted to other men.

In the study, Moltz focused on the metabolism of serotonin, a neurochemical responsible for sexual arousal and behavior located in the hypothalamus.

When serotonin re-uptake was inhibited with Prozac, an anti-depressant, heterosexual men had a significantly greater metabolization rate of the Prozac than did the homosexuals. According to Moltz, this difference in neurochemistry showed that the body dictates sexual preferences, offering evidence that it is not a matter of choice.

The results hold great promise for the scientific community, according to Heino F. L. Meyer Bahlburg, a professor of clinical psychology at Columbia University.  Bahlburg said that the study marks the success of a new technique in the investigation of sexual preferences.

"The remarkably strong association seen in this study between hypothalamic physiology and sexual orientation underlines the promise of functional brain imaging for elucidating the neuroanatomy and neurophysiology underlying human sexual behavior and functioning," Bahlburg said in a news release issued by the University.

Dominique Duncan, a first-year in the College, said that these findings run contrary to common perceptions about sexual preference.

"Most people believe that it's a matter of choice," Duncan said. "For instance, I know people who still aren't sure if they're gay or straight or bi, and it just seems like they will decide for themselves and it has nothing to do with their internal chemistry."

Past studies had indicated links between individuals' genetic makeup and their sexual orientation. Moltz said investigations into a "gay gene" have proved promising but inconclusive, and he believes that the study incorporates too broad a population.