Studies of human body may find causes for homosexuality

by Kevyn Jacobs
June 1996

Is biology to blame for my being gay?

Is there a genetic reason for my emotional and physical attraction to men? Is it based on brain chemistry? Is my brain hardwired this way?

As I have stated in a previous column, I don't pretend to be a scientific expert. I am just an interested layperson with some subjective insight into the subject of homosexuality.

But as I understand it, there is a growing body of scientific evidence that seems to suggest that there IS a biological component to same-gender attraction and behavior.

Here are a few of these areas that are being studied now:


Recent research has demonstrated that the brains of men and women are different in some surprising ways. It has been suggested that women have greater connectivity between the two halves of their brain, as a result of a thicker corpus callosum -- the brain tissue that links the two halves together. It is this greater connectivity that has been suggested as the cause of greater intuitiveness and creativity in women.

This same thickening has been demonstrated to exist in the brains of gay men, suggesting that the brains of men like myself are probably more like women's brains in function than men's.

Another brain difference has been found in the hypothalamus -- a part of the brain that influences sexual behavior and sexual aggression. Males tend to have much larger cell structures in certain parts of the hypothalamus, while females tend to have smaller cell structures.

And again, studies of the hypothalami in homosexual men have found that the smaller, female-like cell structures are present.

This would seem to suggest that homosexual behavior is, in part, influenced by biology. In essence, parts of my brain, as a homosexual male, are hardwired as if I were female.

This is not to say that I wish to be a female -- that is the realm of gender identity, as opposed to sexual orientation, and a topic for another column.

Instead, it merely suggests that parts of the brain that delineate male and female behavior patterns in the brain are not so clearly defined in some.

Of course, this research is by no means conclusive. Questions of causality are not answered -- are brain differences between males and females inborn, or are they socially constructed? Is it possible that homosexual behavior or upbringing causes these brain differences to develop? And do brain differences exist in the case of lesbians, as opposed to heterosexual women?

This research makes it appear that there probably is a link between homosexuality and biology, and that further study is needed.


One of the more interesting recent studies of homosexuality and biology has been in the area of twin studies. It seems that in the case of identical twins, if one is homosexual, then the other has a more than 50-percent probability of being homosexual.

This is statistically significant, especially since fraternal twins and non-twin siblings have much lower probabilities of being homosexual. Since identical twins share identical genetic codes, the suggestion is that even if homosexuality isn't caused exclusively by genetics, there's a strong possibility of there being a genetic component that leads to the development of homosexuality.

Of course, these studies are also not conclusive. One area in which they lack is the study of similar environmental factors twins share. What role did environment have in shaping the similar sexual orientations?


Another area of debate that has arisen lately is the suggestion that hormonal influences on a developing fetus may influence sexual orientation in later life.

It is known that during early pregnancy, certain hormones must be released at certain times by the mother for the fetus to develop properly. Some studies have suggested that certain hormones, either released in excess or in quantities too small by the mother will affect the forming brain in the fetus. These developing brain structures may very well influence the fetus' sexual development.

A recent study found that when pregnant mothers were given certain drugs during recent decades, they were statistically more likely to have daughters who grow up to be lesbian. Discovering whether this is so will require further study, but it seems to support the suggestion that an adult's sexual identity may have been shaped while that person was still in utero.

Whether or not biology actually causes homosexuality is still up for debate, and it is a debate that will probably go on for a long, long time.

My personal opinion is that there is probably a confluence of factors, biological, genetic and environmental, that come together to shape sexual orientation.

In the face of this growing body of evidence, the continuing assertion that homosexuality is a chosen orientation is not very credible.

Frankly, I think I was born this way.

This article was initially published on Monday, March 6, 1995

Kevyn Jacobs is a sophomore in art at Kansas State University. From January to December 1995, Jacobs wrote a queer-themed column in the Kansas State Collegian. The columns are being reprinted in Oasis in chronological order with permission of the author.
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