BY LENORE PIPES

In print | Published December 7, 2006

Since homosexuality is a highly politicized issue, our society is eager to know whether or not it is innate and if it is predetermined by genes. Conservatives might view gayness as a “biological error” because homosexual intercourse seems to be evolutionarily maladaptive since it doesn’t allow propagation of alleles into the next generation.

Gays are not like sterile worker ants either. In view of the kin selection theory, homosexuals don’t seem to spend an exorbitant amount of time and energy indirectly investing in their close relatives. Like many behavioral traits the biological mechanisms behind homosexuality is not well understood because of its complexity. Nonetheless, twin and family studies indicate that there is a genetic contribution to the development of homosexuality. For gay men, if one monozygotic twin is gay, the chance that his twin is gay is 50 percent. In terms of probabilities, this is more than what would be expected by chance and but less than what would determine say, hair or eye color.

Highly-cited examples of the naturalness of homosexuality are the engagements of genital rubbings exhibited by bonobos and cultural acts of male-male genital stimulation in ancient Greece and a tribe in the New Guinea highlands called the Sambia. Although these behavioral acts serve different social functions in each of these examples, they are sustained generation-to-generation through cultural channels. This just shows how once natural selection has created a form of gratification it can come to be manipulated for a different purpose. For example, in ancient Greece, young men were socially motivated to raise their hierarchical status. Thus, the environment can be an extremely powerful influence to diverting from the usual conduits of sexual impulses. Many are familiar with prison to be such an environment where some men seek the closest sexual substitute.

But, does there exist a “gay gene”? Is it correct for the researcher who generated the hype of its existence, Dean Hamer, to wear a shirt that says, “thanks mom for Xq28”? Homosexuality remains an apparent puzzle in the Darwinian paradigm because any genetic inclination to shun heterosexual opportunities should have been selected against a long time ago. Maybe the environment in which this trait was evolutionarily adaptive doesn’t exist today or maybe its cause is not directly genetic but determined by other conditions like the womb environment.

Causing further confusion is the existence of homophobia — why aren’t men overjoyed from the confessed withdrawal from sexual competition? Just because DNA markers on the X-chromosome are linked with male sexual orientation doesn’t mean that one gene, regardless of environment, makes a man inevitably and determinedly gay. Even if there was such a gene or combination of genes, natural selection would want some other counterweighing advantage such as increasing fertility when inherited by women.

People are so worried about whether there is a “gay gene” because it might be possible for prospective parents to try to select against it or engineer to change it. What is apparent about homosexuality is that there is a combination of biological hardwiring coupled with environmental influence that strongly leads some individuals to a homosexual lifestyle. From a purely scientific view, homosexuality is one of many behavioral traits, like handedness, that colors our studies on human diversity.

Lenore is a junior. You can reach her at lpipes1@swarthmore.edu.

« RETURN TO OPINIONS

« PREV ARTICLE | NEXT ARTICLE »