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Science and Medicine: Brain Chemistry

Rob Stein
Washington Post Staff Writer
Monday, June 23, 2008 11:00 AM

Washington Post science writer Rob Stein was online Monday, June 23 at 11 a.m. ET to discuss a provocative new study that found striking differences between the brains of homosexuals and heterosexuals in both men and women.

He was joined by Marc Breedlove, a professor of neuroscience at Michigan State University.

Read more in related story: Brain Study Shows Differences Between Gays, Straights

A transcript follows.

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Rob Stein: Hello everyone. Thanks so much for joining us today to discuss this provocative new research. This a subject that always seems to generate a lot of interest -- and controversy. I see there are already a lot of questions. Joining me today to help answer some of them is Marc Breedlove, a professor of neuroscience at Michigan State University. So let's get to it.

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Washington, D.C. : Gentlemen,-very interesting and stimulating research, I guess for pure research it's fine. However, I am not sure where we are going with this, are we saying we want to come up with a way to prevent the effect? This research helps me understand why women seem to zero in and identify gay men much faster than a man. Contrary to a lot of religious and right wing types, I have always believed it was not a choice, but rather a physiological effect.

Rob Stein: None of the researchers I spoke to for this story said they hoped this work would lead to attempts or efforts to prevent this effect. In fact, many expressed concern that the work could lead to that interpretation -- that somehow homoexuality was something that could be treated by manipulating hormones.

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Munich, Germany: Once in school, a teacher told my class that many successful fashion designers are homosexual men, because they have the creativity usually attributed to women and the business acumen found in men. But I'd also heard that creativity is centered in the right side of the brain, which is larger in heterosexual men.

Has there ever been a study to determine if women and gay men are more creative than straight men?

Marc Breedlove: Q#2 I don't know of any study of creativity in gay vs. straight people. however, it is true that gay men are much more interested in creative careers than are straight men.

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Menomonie, Wisc.:

If this study can be proved conclusive, wouldn't have an enormous impact on the legal implications of such factors as gay marriage?

This would prove that homosexuality is NOT a choice; thereby NOT immoral. It would prove that it is a natural part of a person's fiber.

Therefore, any laws prohibiting gay marriage might violate gay people's rights.

Would you agree? Thank you.

Rob Stein: There's no question that one of the possible implications of research like, according to gay rights activists. They hope that it will help dispell the notion that being gay is somehow a "choice."

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Gainesville, Va.: I have a question that has bothered me since some of these studies of a genetic basis for homosexuality first came out. If one believes in evolution, and that evolutionary processes tend to favor genetic stuctures which reproduce themselves, and if it is true that homosexuala tend to produce fewer offspring than heterosexuals, would not any genetic basis for homosexuality be slected against and disappear over time.

Marc Breedlove: This question comes up a lot, but I don't really think it represents a problem, really. First of all, remember that about 10% of the population is infertile, and clearly natural selection has not eliminated those problems. What Darwin said was that *every* population *always* has individuals who vary in reproductive competence. If 10% of the population is infertile, clearly 5% of the population could be gay and no "exception" to natural selection is needed.

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Washington, D.C.: Hello - with the increasing evidence that in utero hormonal influences affect sexual orientation, isn't there a logical (if disturbing) next step of preventing homosexuality by countering those influences?

Marc Breedlove: none of the researchers I know of have any interest in developing a "therapy". And most of us, including me, think that no such therapy would work. Development is so complicated, and any intervention would be so crude, that no one would want to try.

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Harrisburg, Pa.: Does this study give credence to the notion that homosexuality is a disease, or a "genetic anomaly?"

Rob Stein: No one that I spoke with would interpret these findings that way, though at least one researcher expressed concern that this work could lead some to think that homosexuality could somehow be treated, perhaps by manipulating hormones. But I have not heard anyone actually voice that interpretation.

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Rockville, Md.: I am a fraternal twin (male) whose twin was a female. What would you expect my sexual orientation to be?

Marc Breedlove: Knowing that you have a fraternal female twin does not tell me anything about your odds of being gay. Nor would knowing you have a male twin. The only sibling relation we've found is that having older brothers makes it more likely that a man will grow up to be homosexual.

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Marc Breedlove: My particular opinion is that, even if homosexuality was a choice, as it harms no one, why should people who choose that give up any rights? However, the evidence indeed keeps mounting that things outside our control, like how many older brothers you have, make a difference in what sexual orientation you develop.

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San Jose, Calif.: From my biological psychology I learned about the brain's elasticity and its ability to adapt to different situations. If I do something that makes me happy and you take a snapshot of my brain during that time you'll see a lot of serotonin.

But did my serotonin cause me to be happy or did MY DECIDING to do something happy cause me to release serotonin. Am I correct with this reasoning? If so then gay people's brains adapt to the CHOICES they make?

Rob Stein: You're absolutely right that there is a chicken-and-egg issue involved in this kind of research. Did the differences in the neurobiology that the researchers found result from the subjects' sexuality or is it somehow illustrative of some fundamental differences in their brain that helps account for their orientation? The researchers chose to study certain aspects of the brain that are not necessarily involved in sexual orientation to help avoid that problem. But some researchers say it didn't fully avoid that issue.

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Washington, D.C.: Thanks for explaining why I have less in common with my lesbian sister than I do with hetero women, maybe Sex in the City being about gay men was right in that we're most like straight women. You go, girls.

Rob Stein: The researchers who conducted this study stressed that they don't know what kind of affects on behavior the differences they detected might have. But some researchers say the differences in the connection between the amygdala and other parts of the brain might help explain some behavioral tendencies in gay men and women, since the amygdala is involved in processing emotions.

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St. Louis, Mo.: If, as historians have indicated, "gays" and "homosexuals" only emerged as a category of persons in the late 19th century, did nobody before that time have the kinds of brain chemistry patterns your study claims to detect among those who identify as gay today?

Marc Breedlove: What historians agree on is that homosexual behavior has existed for about as long as we have recorded history. What's in dispute is what sort of social identity people who preferred homosexual activity held. But if there have always been people who preferred homosexual attachments, then that's perfectly consistent with there being biological factors that affect orientation, and with the idea that those factors have always been at work in a minority of people.

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New Haven, Conn.: I'm sure the brains varied within groups. A key question on potential validity of a small sample (beyond sampling bias, etc.) is how much variation there was within a group - tighter alignment with less variation in each group tends to make us want to trust the results more. E.g. How many of the 25 hetero women had brain patterns that were more like those of the hetero men than their own group? - This tends to indicate greater variation in the hetero woman group. But we would expect there to be some differences in female vs. male brains due to hormonal differences. The key question then becomes: How many of the homosexual men (or women) had brain patterns that were more like those of the hetero women (or men)? Did a few outliers influence the result? The NAS article, being juried?, probably addressed this, so you might be able to read the answer.

Marc Breedlove: For these sorts of studies, the sample sizes in this latest study were quite good. And the statistical tests indicate that differences as large as these between gay and straight people are very unlikely to be due to chance alone. The stats are quite solid.

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Rockville, Md.: I read a report some time ago about the influence of fetal position in the womb on the behavior of the rat. Are you familiar with this research?

Marc Breedlove: That research began down the hall from my lab by my colleague Lynwood Clemens several years ago. Yes, a female rat that is carried between two brothers in the womb will be less likely to show feminine behaviors and more likely to display masculine behaviors as an adult. There were fewer, more subtle effects on males. The conclusion was that testosterone from the brothers affects the brain of the sister.

There's no evidence that girls with a twin brother are more likely to be gay, but there is evidence, from my colleague Kelly Klump, that they are less likely to have eating disorders like anorexia.

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Philadelphia, Pa.: Are there also physical conditions that are related to the brain chemicals? I have read that the release of chemicals that also indicate sexual orientation also make subtle body changes, such as the length of the second and fourth fingers. Is this true or is this a myth?

Rob Stein: Yes, there has been research comparing a variety of physical characteristics between homosexuals and heterosexuals, including finger length, and found differences. In addition to differences in the ratio of finger lengths, some studies have found differences in imperceptible clicking sounds in the ears and the direction of "hair whorls" on the back of the head. This is cited as further evidence that some fundamental developmental differences exists between homosexuals and heterosexuals.

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Rob Stein: I'd like to add a little more to the question from Gainesville, Va. Some researchers have suggested that there could be an evolutionary explanation for homosexuality. The theory is that society needs a certain proportion of the population that does NOT reproduce so they can focus on providing other important functions to help the species as a whole survive and thrive.

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San Bruno, Calif.: Years ago I saw a study on transgendered brains. Obviously, this has nothing to do with sexual orientation. The study of a very small group found a microscopic portion of the brain that was found only in folks identifying in the gender other than that in which they were born. Do you know anything about that?

Marc Breedlove: Yes, there was a study of a small group of male-to-female transsexuals that found that a part of the brain that is smaller in women than men was also small in the M2F subjects. This region cannot be seen with non-invasive methods, but can only be seen after death by sectioning the brain and using a microscope. So it's no surprise that no one else has yet gathered a sample to try to replicate this. It remains an intriguing finding.

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Rob Stein: If New Haven, Conn. (or any other reader), is interested in seeing some of the details first-hand, the abstract to the paper in the Proceedings of the National Academy of Sciences can be accessed with the link provided in the story.

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Gay creative careers: One possible explanation for gay people (male and female) being more interested in creative careers than straight people is that we don't (or didn't, this is changing) envision the need to support a family and thus have steadier work or more guaranteed income than the arts offer. So fewer potential creatives get weeded out among gay people than straight people.

Sounds simplistic to me, but could be one strand in an explanation.

Marc Breedlove: This is a potential factor, I agree. But, on average, gay people have more education and higher salaries than straight people, so I don't think this could be a big factor.

Also the studies of career interest I mentioned, mostly by Richard Lippa, really get at *interest*, not just what the people happen to be doing for a living. As psychological effects go, the difference between gay and straight men is a big one.

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Anonymous: How long can it take for help to the victims of gay acts?

Marc Breedlove: I don't know what victims of gay acts you're talking about. In the US, at least, almost the only people who are attacked because of their sexual orientation are homosexuals. I imagine the same is true world-wide.

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Mt. Lebanon, Pa.: I respond to all of my emails, unless they're clearly junk. I don't hold the line up at my favorite coffee joint. I think logic and reasoning superior to emotion and feelings. I hold to scientific principles (I'm an engineer) over the belief systems imposed by religions and governments.

I have changed the oil in my car and changed flat tires on it. I don't watch commercial television (except for ESPN and the History Channel) prefering C-SPAN and PBS to the mindless gibberish offered by the major networks. I don't watch popular science programming as it's too much WhizBang and not technical enough for my tastes.

I don't believe I'm the sole purpose of 15B years of universal evolution. And I don't believe that everything in the galaxy is mine by right, for the taking (i.e., I'm not a Republican).

Quick: which sex do I belong to?

Bonus points: And am I Bi, Gay, Straight, or some other flavor?

See? How hard was that?

Thanks much. HLB

Rob Stein: You obviously make a very good point that stereotypes are very dangerous. That clearly applies to sexual orientation. The stereotype that gay men are more "feminine" and gay women are more "masculine" quickly falls apart. There are clearly many gay men who fit the stereotype of being very "masculine" and many gay women who fit the sterotype of being very "feminine." Studies that have examined behavioral characteristics among gay men and women have, however, found certain tendencies that seem to be consistent with some of the findings in the new research.

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Dallas, Tx: One of the phrases that goes throughout the article is 'tends to', does that mean that at least one brain that had both lobes the same size was on a straight male? And if though there was probably statistical significance, that doesn't make thiss conclusive, does it (if it can be proven wrong)?

Marc Breedlove: This is a great question. What the scientists found was that gay and straight people *on average* differ in this regard. So there was some overlap. This is typical of studies that find differences between gay and straight people and emphasizes that many factors are at work and so no single factor explains all cases.

Also note that because there are probably many causes of homosexuality, there are probably more than one "type" of gay man or gay woman.

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N.C.: Thank you for reminding us about the chicken verses the egg issue, but a part of me still thinks that an individual human being can override genetics or biology. i.e. even if "normal" brain might still be homosexual i.e. not treatable unless it's up to the individual or not created because someone wants to. Thank you.

Marc Breedlove: The question isn't whether a person can change their behavior, or whether society can change a person's behavior--clearly both are possible. The question is whether, having changed the person's external behavior, have you changed their internal desires and outlook. For that, it seems clear that very, very few men can change their orientation.

As another example, if Germany had won WWII and if gays were still being sent to death camps, of course we'd see fewer openly gay people. But that would not disprove the importance of biological factors, right?

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Dallas, Tx: Would the next step to see how accurate this technique for identification is to take images of say 100 or 1000 brains and try to determine sexuality? Have they done that? If so, to what success?

Marc Breedlove: The authors point out that they await having other labs replicate these findings. Time will tell.

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Baltimore, Md.: More on gay men's career choices: I've always assumed that gay men would avoid jobs like auto mechanics or construction work because of harassment issues. But you mentioned that most gay men aren't even interested in that type of job.

Rob Stein: It's not that they are never interested in that type of job. It's more that studies have shown that as a group gay men have a tendency to be more interested than straight men in jobs that are typically thought of as jobs that women tend to go into -- such as teaching and social work. But there are obviously plenty of straight men who go into those fields, as well as plenty of gay men who are mechanics and construction workers.

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Reston, Va.: I wonder about the role of culture in determining sexual orientation. For example, the Greeks' values regarding gay relationships - or the prison culture where homosexuality is regarded as a temporary "fix" to lack of availability of women.

Marc Breedlove: Of course culture has a say in people's *behavior*. What's unclear is whether culture has a big effect on people's sexual *inclination*?

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Arlington, Va.: Regarding reproduction...

You said: "I'd like to add a little more to the question from Gainesville, Va. Some researchers have suggested that there could be an evolutionary explanation for homosexuality. The theory is that society needs a certain proportion of the population that does NOT reproduce so they can focus on providing other important functions to help the species as a whole survive and thrive."

Probably more important in this case is simply that many, many people who identify as homosexual do in fact have biological children (I don't have the figures at hand, but it's not a small number). There are a variety of reasons for this, including marriage to heterosexuals, heterosexual sexual activity as adolescents, non-sexual impregnation (e.g. artificial insemination), etc. If you remove biologically reproducing gays/lesbians from the equation, the percentage of people who do not reproduce because they are homosexual is even smaller. In any event, the assumption that all gay/lesbian people don't biologically reproduce is simply wrong.

Rob Stein: That's absolutely correct, and I'm glad you emphasized that. I was just describing one theory that has been put forward as a possible evolutionary explanation for homosexuality.

A similar line of reasoning has been put forward for menopause -- why women live so much longer than they can reproduce. One theory is the "grandmother effect" -- which is that the species benefits from the caretaking role that grandmothers provide.

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Herndon, Va.: So then, what about people who were homosexuals and became heterosexuals (Anne Heche, for one famous example), or vice versa, or bi-sexuals.

Whom are they kidding? Us, or themselves? And which, then, is the "real" self?

Whatever the biology "says," people ultimately have choice in their sexual orientation and sexual actions.

Marc Breedlove: First, it's clear that women are more fluid in their sexual orientation than are men. And it's also clear, to most researchers, that some people really are bisexual. But most men, when asked, cannot imagine falling in love with the "wrong" sex. And it's clear that many homosexual men who very much wanted to be "normal" and worked very hard to achieve that, could not. I don't believe any of the touted therapies is actually effective in more than a tiny fraction of cases.

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Rob Stein: I think it's worth noting that one of the possible implications of this kind of research are political, obviously. I spoke to someone from the Human Rights Campaign, who said he hoped this research would help dispel the notion that homosexuality is a choice and that people can change their sexual orientation through counseling. At the same time, I spoke to someone at the Family Research Council, who said he was unconvinced by this research and argued that people can change their sexuality through counseling. So clearly this research has not ended that debate.

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Marc Breedlove: About evolutionary pressures on any genes that favor homosexuality, I think my earlier post got lost.

I don't think there's any difficulty understanding how natural selection would tolerate "gay genes." First, remember that about 10% of the population is infertile. That's a much bigger blow to reproduction than being gay. But, as Darwin pointed out, all populations always have people who vary a great deal in reproductive potential.

Also, there is evidence that some genes might favor reproduction in females and disfavor reproduction in males. So, for example, female relatives of gay men have, no average, more children than do female relatives of straight men. So maybe the gene is kept in the population that way.

Finally, note that many gay people do have biological children, for a variety of reasons.

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Cleveland Park: I'm just waking my gay brain up, but the findings seems rather logical. Does it put to rest the idea that we choose our sexual orientation? Probably not, but for me I don't particularly care. I'm Me, and wouldn't do a thing to change it.

Question: Will it change the stigma associated with being queer?

Marc Breedlove: No one knows for sure, but psychological studies find that, the more a person believes biology influences sexual orientation, the more likely they are to accept homosexuality as acceptable behavior. So that potential for lifting the stigma is there.

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Quite an aptonym: Professor Breedlove talking about sexual orientation. Is the focus of your research orientation or do you explore other areas?

Marc Breedlove: I did not choose my name, and I don't think I'm any more obsessed with sex than the average man. I admit that I like my name, but I don't *think* it had much effect on my career choices.

Almost all of my work is with animal subjects (rats, mice, hamsters) and that reflects my lifelong fascination and love for animals (I grew up on a farm until I was in 5th grade). Then in graduate school to study behavioral neuroscience I learned that hormones offered a tremendous opportunity to study how the nervous system controls behavior. I've been studying hormones and behavior ever since.

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Anonymous: On one hand the bible is the book of validation. On the other hand, anthropology has shown that culture with no exposure to the Judeo-Christian or Islamic ethic have homosexuality exist in their culture. So why must we continue to wage this debate or solve this question and not realize it exists? Or, that it may have been a common occurrence since the dawn of time?

I'm a straight male and I never recall having a moment in my life where I said I think I'll be straight and be attracted to females versus the other.

Rob Stein: That is the way a lot of homosexual people describe themselves -- that they had these feelings their entire lives and that they are just part of who they are.

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Mt. Rainier, Md.: I would like to register a quibble about "choice" determining the morality of a behavior. While I don't believe that homosexuality is immoral, since it is between two consenting adults, many other sexual aberations I think should be condemned even though they are not chosen, such as pedophilia. Disease is never chosen, but how it affects others may very well be a moral choice.

Marc Breedlove: This is why I think the question of whether people "choose" to be gay is irrelevant to whether homosexuality should be discouraged. Of course we should consider whether a behavior harms someone else when we make our laws. Note that many laws seem unrelated to this. For example, up to the 1960s many states outlawed inter-racial marriages. What did that have to do with harming others?

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Rob Stein: Well, we're just about out of time. Thanks so much to everyone for all your great questions. As expected, this was a very lively, provocative discussion. I'm sure we'll be back some time soon to discuss it again the next time some new research in this area emerges. I especially wanted to thank Dr. Breedlove for taking time to join us today.

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Marc Breedlove: I need to wrap this up for today, but readers can find out more about my particular research on the web. Just Google "Marc Breedlove" and you'll find our lab web page and lots of other material.

Cheers,

Marc

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