The "Self-Sufficiency Gene"

Another model of how genetics influences sexual orientation is that Xq28 (a region of the X chromosome) contains a gene for the personality trait called self-sufficiency, which in this sense means the iconoclastic, or socially independent. The hypothesis is based on four propositions: Self-sufficiency is a prerequisite for homosexuality in the population we studied; there are differences between gay and straight men in their degree of self-sufficiency; self-sufficiency is genetically influenced; and one of the genes for this characteristic is located in Xq28. As unlikely as it sounds, there is some evidence gathered by other laboratories to support these claims.

The psychologist Raymond Cattell describes self-sufficient individuals in the following terms: ". . .temperamentally independent, accustomed to going their own way, making decisions and taking action on their own. . .they discount public opinion...." The opposite of self-sufficiency is "group reliance," which describes "joiners," who depend on social approval and admiration for self-esteem. Cattell measured these traits with what he calls a sixteen-personality-factor inventory, or 16PF. He got data for the scale by asking subjects to respond to statements such as "Most people would be happier if they lived more like their friends and did much the same things as others."

Based on this specific definition, our subjects--all openly gay men--must have been self-sufficient. They not only had to be sexually attracted to other males, they had to ignore society's scorn for homosexuals and acknowledge their orientation to themselves, to friends and family members, and to an outside researcher.

The second proposition, that self-sufficiency is correlated to sexual orientation, has been tested by administering the personality inventory to gay and straight men. In each of three studies conducted in Australia, the United States and South Africa, gay men scored considerably higher than straight men for self-sufficiency. This "positive" trait was one of the most significant differences between gays and straights in two of the studies, and even in a 1962 study for the "Australian Commission to Study the Problem of Homosexuality," which concluded that homosexuals have a "criminal" personality profile.

The role of genetics in self-sufficiency and other personality traits has been approached primarily by comparing identical and fraternal twins. The main conclusion is that virtually all personality traits, including those that contribute to self-sufficiency, are to some extent influenced by genes. The usual estimate are that genes contribute between 20 percent and 60 percent to personality, while other factors, such as family life, explain the rest. Although the methodology of these studies has been criticized, the accumulated evidence indicates that personality traits are at least somewhat influenced by genes.

The final proposition--that self-sufficiency is specifically influenced by a gene at Xq28--was based on a tantalizing but still inconclusive experiment conducted by Jonathan Benjamin, R.H. Belmaker and their colleagues at Be'er-Sheva Mental Health Center in Israel. Benjamin, who conducts psychiatric screening tests for the Israeli army, identified 17 pairs of brothers in which at least one brother was color blind. Because the color-vision locus is located in Xq28, it allowed him to determine which brothers shared DNA sequences in this region of the X chromosome.

Benjamin administered the Cattell 16PF test to all the brothers and tallied up the scores on each of the sixteen items. If a gene in Xq28 influenced one of the personality traits, he expected the Xq28-concordant bothers (both color blind) to be more similar to one another than the pairs with only one color-blind brother. This pattern was observed for only one area of the test: self-sufficiency.

In early 1994, we were sending out the 16PF questionnaire to all 40 pairs of gay brothers in our original study and administering it to all new volunteers. We also were collaborating with Jonathan Benjamin to replicate his experiment, using a much larger group of heterosexual brothers and using real DNA markers instead of the "poor man's marker" of color blindness. This was a great deal of effort to base on a hunch, but my own interviews for our study had turned up some interesting tidbits that now were beginning to make sense. For example, there was the case of the brothers I'll call George and Albert.

George answered the phone on a summer day in 1992 and gave me directions to the house he shared with his brother. He added, as a sort of caution, that his brother was "kind of conservative." I followed the directions and pulled up in front of a 1950's ranch-style house in a quiet residential neighborhood in a small southern hamlet. The grass was green and well tended, and pink roses swayed alongside the white picket fence.

I rang the bell and was greeted by a man who was naked from the waist up. Two shiny metal rings hung heavily from pierced nipples, and there were thinner rings through his lip and eyebrow. His torso was busily tattooed, and when he turned to lead me into the living room, I noticed that they extended across his back and included a German cross and wreath of snakes and bullwhips.

"You must be the less-conservative brother," I ventured.

This was George, and he was not a conventional guy. At age 13, he said, he seduced his pastor. At 18, he left home for New York to begin a career as a stripper, a hustler, and a gigolo. When I asked him to estimate his lifetime total of sexual partners, he said that he had thought quite a lot of about the number. Including every contact at bathhouses, sex clubs, and backroom bars, he figured it was 10,000 to 20,000 partners, including several hundred women he'd slept with for money.

When I ran the standard questionnaire on him, including demographics such as educational level, I was impressed to hear he had gotten a master's in New York.

"Not a master's," he corrected me. "A master. I've got a master in New York."

Even with a history of sadomasochism, extensive drug use, and multiple partners, George tested negative for the AIDS virus. If there is a gene that resists the AIDS virus, I thought, George would be a good place to start the search.

When Albert appeared, I thought he was George's accountant, or maybe the piano teacher, rather than his only brother. Prim and proper, Albert said he had a 9-to-5 job, went to church on Sundays, and was the one responsible for keeping the yard so neat.

The one thing Albert shared with his brother was an attraction to men, which he first recognized at age 5. For the next twenty-two years, however, he did everything possible to deny those feelings to himself and to others. When he fell in love with a college classmate and was rejected, he sought solace in becoming a Jehovah's Witness. When his homosexual attractions still wouldn't go away, he joined the marines to prove he was a real man. Only after an emotional breakdown, which led to counseling from a sympathetic psychiatrist, did Albert begin to accept his sexuality. As a gay man, he still struggled to lead a conventional life, and following the breakup of a six-year relationship, he remained chaste because he preferred a monogamous relationship.

According to the definitions used in the personality test, Albert was group oriented, while George was the very picture of self-sufficiency: insensitive to, if not downright disdainful of, social norms. When we tested their DNA, we found that Albert and George not only had different personalities, they had different versions of Xq28.

Since both men were gay but had different versions of Xq28, perhaps the gene was influencing something related to their psychological adjustment to their homosexual orientation rather than their sexuality per se. For example, perhaps during childhood they both developed gay fantasies, for whatever reason, but only George had a version of Xq28 that led him to indulge those fantasies. Albert, on the other hand, had a different DNA and suppressed his gay fantasies to be more "normal."

This analysis is purely a guess, but it suggests an interesting way of looking at how an inherited personality trait unrelated to sex might influence sexual orientation.

"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, Bethesda, Maryland.
Special thanks to Tim Robbins for contributing this piece.