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Dr. Marc Breedlove

Dr. Marc Breedlove is the Rosenberg Professor of Neuroscience at Michigan State University in East Lansing, MI. He is recognized as one of the world’s leading experts on human sexuality. He received his B.A. in psychology from Yale University in 1976 and his Ph.D. in physiological psychology from UCLA in 1982.


Is homosexuality a choice?

You don’t choose who to have a crush on. It chooses you. It just kind of falls on you. Why would you expect it to be any different for people who are gay than it is for people are straight?

Anti-gay organizations like to say homosexuality is learned because “there is no gay gene.” How would you respond to this line of thinking?

As to the question of whether there is a gay gene, it depends on what you mean by that. Have we found a gene where when a person inherits it they will for certain be gay? No, we haven’t found such a gene. There may or may not be one. But we do know that there is a gene on the X chromosome that has been proven to have an influence on sexual orientation in men. What’s more, we know that there are many genes that influence sexual orientation in people. Probably not just one, probably a lot. And, it would probably be the sort of situation where whether or not you are gay depends on which particular combination of genes you get.

The example I like to use is, to talk about height. The estimates are there are 150 different genes that influence height. So, is there a gene for being tall? A gene, if you get that gene you will be tall no matter what? No, there probably isn’t a gene for being tall. But, does that mean there is no genetic influence on height? Of course not, that would be silly. Of course, there is a genetic influence on height. Of course there is a genetic influence on sexual orientation. The data are really completely firm.

What role do hormones play in sexual orientation?

There is ample evidence that hormones play a role in the development of sexual orientation. For example, there is lot’s of indications that girls who are exposed to testosterone before birth are more likely when they grow up to be lesbians. Why are there differences between gay and straight men? Are those due to prenatal testosterone? The evidence for that isn’t very good. So, it’s not that the gay men didn’t see testosterone. Rather it seems that the gay men somehow were responding differently to the testosterone they got before birth. Why would they respond differently? Well, the most likely explanation is that the genes they carry are such that they respond differently to testosterone than the straight men.

The more we know about the development of the nervous system, the more we see the importance of development in the womb. You might think that it is a fairly simple environment, but it’s not. It is a very complex environment that is being influenced by lots of different factors. Environmental factors outside the mother. Environmental factors inside the mother. And environmental factors that are brought by the fetus itself. So, it’s clear that there are lot’s of different influences going on before birth inside the uterus that are not necessarily easy for us to track down. One of the ways that we know that there must be such influences is if you look at identical twins who have the same genes and yet they don’t necessarily come out the same. What is different about them? It can’t be their genes. It has to be that their uterine environment was a slightly different one from the other. Sometimes, that can make a big difference in the lives of those individuals as they grow up.

Anti-gay organizations like to say that distant fathers and overbearing mothers cause homosexuality. What does the latest science say?

Sigmund Freud had an interesting theory about why some men grow up to be gay. His theory was they had an overprotective mother who sort of smothers them with love and keeps them from identifying with their father. And later people decided that in addition that maybe having a cold and distant father would lead a boy to grow up to be gay. In fact, scientists have looked for such correlations. They have looked at such family structures to see if there is any correlation between those sorts of family conditions and the probability that a boy will grow up to be gay. And, the answer is none, you can’t find it.

The Religious Right claims that homosexuality is unnatural. What is the scientific view?

If you hear someone say that homosexuality is unnatural, you can be pretty sure you are not listening to a scientist. Because, scientists know that homosexual behavior does happen in the wild all over nature. Lot’s of different animal species have displayed that sort of behavior. And there are even some cases where animals not only display homosexual behavior every once in a while, but where an individual will clearly prefer homosexual relations over heterosexual relations. Are those animals common? No. In general the animals who are showing lots of homosexual behavior, indeed, tend to be a minority of the animals out there. But it certainly happens because, you know, that’s what nature is really like. It’s full of variety.

As a scientist, what is your view on programs to change one’s sexual orientation?

I don’t think the evidence is very good that anyone can change their sexual orientation. Does this mean that a highly motivated individual couldn’t go to a group and through a lot of work change their behavior? I imagine so. I imagine they could. But that doesn’t mean they change their sexual orientation. And, if you really want to know whether anyone can change sexual orientation, if you really look into those reports carefully, the data aren’t very good. I would say that it’s not likely that it ever worked. And it certainly doesn’t work for most of the people who try it.

What is the future of research into the origins of sexual orientation?

It is true that we are having more findings all the time about the role of biology and sexual orientation and I imagine it’s just going to continue. Will we understand everything about sexual orientation soon? I don’t know, that’s a big question. We don’t understand everything about very many biological processes. We certainly don’t understand everything about childbirth or cancer or almost any process that any of us really find interesting. So, I think the great thing about being a scientist is there is always plenty of stuff we still don’t know. The second great thing about being a scientist is that with the right training, you have at least a fighting chance of finding out things you didn’t know before. That’s what makes it fun.