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Dr. Dean Hamer

Dr. Dean Hamer was an independent researcher at the National Institutes of Health for 35 years, where he directed the Gene Structure and Regulation Section at the U.S. National Cancer Institute. In 1993, he published a landmark paper showing that the Xq28 marker on the X chromosome was linked to homosexuality. Dr. Hamer received his Ph.D. from Harvard Medical School.


As the researcher who showed a genetic link to homosexuality, your research is often distorted.

I think that groups like Focus on the Family are misusing the idea of science to promote their own cultural and religious ideas. The science is really convincing that genes and biological factors are very important.

Anti-gay activists love to say, “there is no gay gene.” What is your response?

People on the right often say “there is no gay gene.” They will even cite me when I say there is no single gay gene. And that is correct, just as it’s true that there is no height gene. There is no eye color gene, and there is no hair color gene. All of those traits are controlled by a large number of genes that interact with one another and interact with the environment. But that doesn’t mean that those traits aren’t largely genetic. So, there are probably many different genes that affect sexual orientation. We don’t know what they are yet. We don’t know exactly how they work. But there is very convincing evidence that they do exist.

Why isn’t there more research on the etiology of sexual orientation?

The main thing that’s holding back research on sexual orientation now is the lack of funding. And that is largely because the right wing so vehemently opposes this type of research. If we had the same amount of research on the ‘gay gene’ as we do on a lot of other genes for behavioral traits, we will have a breakthrough very quickly.

Anti-gay organizations like to claim environmental factors cause homosexuality – such as bad parenting or sexual abuse. To make their point, they often cite scientists who use the term “environment.”  But what do scientists actually mean when they use this word?

The environment could be something like having measles when you are three years old. The environment could be the exposure to hormones in the mother’s womb. It could be anything that is not inherited. One of the great things about behavioral genetics is that it can tell us not only whether a trait is genetic, but also whether it is environmental and what type of environment is important. And geneticists distinguish between shared environment which is things like the way parents treat children or the schools that they go to, or whether or not they go to the Cub Scouts, and other more random environmental factors.

All of the evidence shows that there is nothing in a person’s upbringing that causes them to be gay. Just like there is nothing in a person’s upbringing that causes them to be straight. What we do know is that none of the factors that used to be suspected like having a father that was distant, having a mother that was too close, playing too much ball with Sally or not playing enough ball with Tommy — we know that none of those are important. None of them have held up to careful controlled research.

Talk about factors other than genes that play a role in sexual orientation.

In addition to the genetic research, there have been a large number of studies of other traits that seem to be correlated with sexual orientation. This includes certain acoustic clicks in the ear. The length of different digits, handedness, and so on and so forth. And all of these are probably markers of underlying sexual development events that are important for sexual orientation. So they may not necessarily cause a person to be gay or straight but they are related to the same biological pathways. I think that the critical point is that none of these are choice, none of them are even learned. These are biological markers for something very deep that goes on inside people.