Thursday, May 14, 2009

The "Gay Gene" Part II

This is Part II on the discussion of the genetics of sexuality. Part I is here.

Medical and psychological research literature have underwent major shifts in regards to homosexuality (and bisexuality). Once it was deemed as a psychiatric illness to be "fixed," and gays "converted" into straights. This thought prevailed until somewhat recently (in the US).

A recent NY Times article questioned the classical Masters & Johnson "gay conversions." It questioned the science and reality behind the studies, suggesting that the conversions may have been faked. These conversions may have been "at best composite case studies made into a single ideal narrative, and at worst they were fabricated."

Yet despite this and a shift away from homosexuality being a psychological "problem," some psychological therapists still attempt to "help" homosexuals and bisexuals become heterosexual. In this article, Gay 'cure' still sought by some therapists, it was found that 1/6 of UK therapists have attempted to "help" gay people become straight. It certainly doesn't help that another recent article, Some Gays Can Go Straight, Study Says, only seems to reinforce the notion that, if a gay really wants to try to become straight, it may be possible. I have not read the primary literature of the study, I do not know the design or the biases, and I'm certainly not versed in psychological or psychiatric research, thus I cannot personally comment on how valid the study may be. However, this is not the focus of this post - it is not my purpose to prove or disprove a study. I shall merely mention them as food for thought.

Down to the biology of it all. What does the literature say? What has the body of scientific knowledge determined about the "biology" of homosexuality? One thing is for certain: there is no single "gay gene." In fact, there are almost certainly many genes that influence sexuality. Furthermore, are there environmental factors that influence sexuality? Research hints that there might be. First things first.

Genetics and Sexual Orientation
Article 1: Genetics has a role in determining sexual orientation in men, further evidence
In my last post, I posited the simplification that a single gene governs a single trait. Science now knows this to be false for most (if not almost all) genes. A single gene may affect several traits, and a single trait may be affected by several genes. Scientists have looked for correlations to see what physical traits appear to be more common in gay men compared to straight men. What have they found?

Left-handedness tended to be more common in gay men (39% higher, as quoted here, thus about 14% of gays are left-handed compared to 10-11% of the general population). Notably, left-handers and gay men tended to have a larger corpus callosum. The corpus callosum connects the two hemispheres of the brain, allowing greater communication between the two halves of the brain. Each half controls the opposite half of the body (e.g. left hemisphere of the brain controls the right side of the body) and "specializes" in different kinds of thinking (e.g. language is in the left, music is in the right).

What does this suggest? Possibly that whatever genes affect sexuality also affect the brain and handedness preferences. Of course, it makes sense that genes affecting sexuality primarily act on the brain. But this is hardly fool-proof, as not all homosexuals (most aren't, in fact) left-handed, nor do all homosexuals have a larger corpus callosum. The genetics is incomplete here.

Genetic Regions Identified
Article 2: Genetics regions influencing male sexual orientation identified
A study by Mustanski has identified stretches of DNA on 3 chromosomes - 7, 8, and 10 - that may play a role in affecting sexuality. Quick note: in every cell in our body (excluding the germ cells - aka sperm and egg) we have 23 pairs of chromosomes. 22 pairs of chromosomes are somatic (non-sex chromosomes) and the 23rd pair is the XX or XY chromosome pair. This study has found that these 3 stretches of DNA on chromosomes 7, 8, and 10 were shared in about 60% of gay brothers in the study, compared to the expected 50% by random chance (assuming no genetic linkage).

This suggests that there is indeed something genetic to sexuality. Specific genes have not yet been identified within these 3 regions, as that's actually pretty difficult to do still. However, some words of caution: 60% is not that much greater than 50%. Thus the genetic effect observed here is still somewhat weak and alone cannot explain the whole story. Additionally, it also means that these genetic regions are not shared among gay brothers 40% of the time. What's going on here?

Genetics and Environment
Article 3: Genetics, environment shapes sexual behavior
This article suggests that both genetics and environment play a role in determining sexual orientation. In the study mentioned, about 3800 same-gender twin pairs were studied in Sweden.

The study found that genetics accounted for 35% of male homosexuality while non-shared environment accounted for the remaining 64% (I don't know what happened to that last 1%). Interestingly, genetics only accounted for 18% of female homosexuality while non-shared environment accounted for 64% and shared family environment accounted for 16%.

The study is, like any study, not without flaws and limitations. But it's certainly worth noting how genetics could account for so little of sexuality (still a significant portion, but certainly not all). How does one proceed in formulating a model of genetics and sexuality from here? Furthermore, the study population was pretty narrow (genetically speaking - all from Sweden), could this study be replicated in several other populations?

Article 4: Researchers revisit male bisexuality
For the vast majority of the articles above, bisexuality had been completely ignored. Only the dichotomous heterosexuality/homosexuality were more or less assessed. Part of the problem is certainly finding and identifying bisexual individuals.

This article brings back into the foreground the 6-point Kinsey scale, allowing a spectrum from "completely straight" to "completely gay." But how would a spectrum of sexuality like this fit into the results from the articles above, much less a genetic model?

So many unanswered questions. Clearly sexuality is determined by multiple genes. But what is the effect of each individual gene? How strongly do they contribute? And if genetics seemingly contributes so little (at 35% for men), then are people really "born gay?" Is there a way to modify the environmental factors, either willingly or not? Does the greater impact of environment mean that one can, in a sense, "choose" to be gay? I'm still going to say "no" to that last question.

And then there's Part III, where I attempt to present a somewhat plausible genetic model that accounts for environment . . .


naturgesetz said...

"Clearly sexuality is determined by multiple genes."

Doesn't "determined" overstate it, especially in light of the Swedish study? Wouldn't it be better to say that "sexuality can be (or maybe 'is') influenced (or 'affected') by various genes"?

Thanks for making the effort to research the subject, digest the literature, and post the findings here.

I recall a study of identical twins separated at birth. Their sexual orientation was the same in more than what was found in a sample of other siblings separated at birth; but it was not the same in a significant percentage of cases. All of which suggests a genetic component, but other factors being involved as well.

Mr. HCI said...

The Spitzer study is hardly "recent." The date on that article may be this month but note there is no year. It was presented in 2001 and was majorly flawed. In addition, anti-gay organizations (and reporters, apparently) have twisted the "findings" to their own ends, often in complete opposition to what Spitzer concluded. Here's a good page with links to many, many articles about the study. You can signup for a free, one week preview at and download the study itself in HTML format. I just did but haven't had time to properly read it, yet.

In brief, however, only 200 participants were involved. All claimed to be success stories and most were married at the time the interviews were conducted. Note that the inclusion of only those who claimed to have changed is going to massively skew the results towards therapy being a viable treatment.

From An analysis of Dr. Spitzer's study at

Of the 200 subjects, 86 had been referred to Dr. Spitzer by conservative Christian groups specializing in converting homosexuals. NARTH referred 46 subjects. Some other sources provided 68 to make the total of 200. It is apparent that the individuals that Dr. Spitzer interviewed were hand-selected from a very large group of persons who had either a homosexual or a bisexual orientation. Those who had been unable to change their sexual behavior would not been involved in the study.

There are more than 1,000 professional therapists who belong to NARTH. Assume that the average member has treated 50 clients a year for the past five years. That means that there are over 250,000 clients from which NARTH could select subjects for this study. Assuming that reparative therapy had a "cure" rate of 0.02% then NARTH would have been able to provide the approximately 50 "successful" clients to this study. But a cure rate of 0.02% can be expressed as a failure rate of 99.98% -- not a promising form of therapy! If one considers the anecdotal accounts of gays and lesbians who have committed suicide after failed reparative therapy, then it becomes even less attractive.

Zee said...

Mr. HCI, how is it so hard to accept that maybe some gay people aren't cut out to be gay? He brings up a valid point. Imagine going to a psychologist and having them tell you that you can never be what you want to be. Also regardless if they are a minority, does that make their existence and experience less important? How is it that people can promote being accepted and then turn around an not accept others? How does depreciating somebody else make you any different than the bigots who depreciate the existence of LGBT people?

Mr. HCI said...

Zee, you've got what life gives you. If you're left handed and you don't want to be, you can force yourself to learn to write with your right hand, but you'll still be left-handed.

You say, "Imagine going to a psychologist and having them tell you that you can never be what you want to be." Well, that's much kinder than telling someone they can change but it will take years and most likely won't work anyway. Many people who go through the "therapies" espoused by the "ex-gay" community end up psychologically damaged and worse off than they were before.

I have extreme doubts that anyone who claims to have changed their sexual orientation actually has. Once can answer questionnaires and lie quite easily. I have yet to hear of any "ex-gay" person submitting to any kind of scientific testing. I'll believe them when homosexually oriented situations and/or materials do not excite the areas of the brain stimulated by sexual thoughts and/or when no rush of blood to the the genitals is detected in the same situation.

Here's what really rubs me wrong about the whole thing, though:

Organizations like NARTH and "ex-gay" groups advocate the denial of equal rights to homosexuals because (some) gays can (allegedly) change their sexual orientation and, therefore, they do not deserve equal rights to heterosexuals. If they didn't have an agenda to eliminate the homosexual population, I wouldn't have a problem with them.

I think my asserting that they are not being truthful is far more tolerant than their assertion that we don't deserve equal rights.

On a side note: have you ever looked into to the details of their much vaunted "Reparation" or "Conversion" Therapy? If making close, non-sexual friendships with straight males and having a romantic, sexual relationship with a female would turn me straight, I'd not be participating in this discussion.

Zee said...

I will totally disagree with that first statement. My father was technically born left-handed but if you ask him to write with his left hand now, he can't. Depending on how you define left-handed determines if that person is "still" left-handed. This whole analogy is subjective and flawed.

I disagree. It is aganist the basic spirit of America to accept that you have no hope. In fact somebody telling me that would make me more motivated to want to change.

I disagree and i think that some have. I have no right to question their lives and nor do you. It is no different than people question if somebody is pretending to be bi-sexual. Also that standard is totally un-reasonable because that would stimulate straight men as well. Humans as a whole are still sexual and few are exclusively homosexual or heterosexual.

I am not going to hate somebody for their beliefs either. Hate does nothing for you.

I disagree again. There are no levels of tolerance. I whole-heartily reject the notation some intolerance is ok and others are not.

If it works for some, good for them. We should be happy for them.

Mr. HCI said...

Where did I say anything about hating anyone??

I am not going to be happy for someone who claims to have changed then uses that claim as an excuse to turn around and attack my rights.

Have you checked any ex-gay websites? The ones I've seen have all been full of anti-gay propaganda. It's not enough for them to want change for themselves, they want homosexuality eradicated.

THAT is hate.

Mr. HCI said...


My statement that ex-gay groups are playing fast-and-loose with the truth is not intolerant. It is a statement of opinion based on years of observation.

Advocating legally denying equal rights to homosexuals, on the other hand, is a perfect example of intolerance.

Zee said...

Yes i have checked ex-gay websites. And I don't think it is a reason to hate them. They will believe what they want. It would only be natural for somebody who "overcame" homosexuality to assume others can. This is obviously a flawed assumption but screaming at them makes you no better than them.

I think the idea that we shouldn't be more accepting of ex-gay people is intolerant. Promoting the idea that those people's livings are a lie and should be disregarding is intolerance. So yes, what you said is intolerance. (that was were i was coming from).

Mr. HCI said...

Assuming others can change their sexual orientation is a far cry from insisting that others do it. The fact that ex-gay organizations advocate limiting the rights of homosexuals who either don't try to, or have tried but couldn't, change is proof enough that they they are not interested in showing us any tolerance whatsoever.

Furthermore, while it may be natural for them to think it is possible for others to change, that does not make it acceptable for them to disseminate falsehoods about homosexuals to further their agenda.

Asserting that I think they are not being honest about some things and are definitely lying about others is not screaming at them, btw.

Anonymous said...

Mr. HCI said...
Zee, you've got what life gives you. If you're left handed and you don't want to be, you can force yourself to learn to write with your right hand, but you'll still be left-handed.

You see the problem with this is that our community is often referred to as the LGBTQ.

That "T" is a problem for that statement you just made. I'm surprised that people don't see this!

You see we have people insist to their last breath that sexual orientation cannot change.
They might even call people who experience change "liars" or "really bisexual" (if the're generous).

But people who are born male (Xy) or female (XX) claim to have been "born in the wrong body" all the time. And their experience is accepted and promoted!

Yet sex is explicitly genetic while sexual orientation only hopes to be!

In other words, how can someone explicitly male claim to be "born with the wrong sex" and go to a psychologist in order to "transition" into being "female" (which is biologically impossible) and yet it is "wrong" for someone to be "born with the wrong sexual orientation" and "unethical" for a psychologist to help such a person?

This is blatantly political.

People should be allowed to live their lives however they choose to.

I will believe that my sexual orientation is "normal" when it is treated in a "normal" way by the psychological profession.
Until then it's clear that "science" gives way to politics (and this is why many gays are always anxious about sexual orientation change).

Mr. HCI said...

Apples and oranges! Changing gender through surgery is not comparable to attempting to change sexual orientation via therapy. It's like comparing fixing a cleft palate with taking an anger management course.

I do not insist that sexual orientation cannot change. On the other hand, I have yet to see credible evidence of it and plenty of evidence against. As far as I know, all therapies to change sexual orientation have a religious base, not a scientific or medical one.

The Spitzer study referenced here included only people who claimed to have changed and the sampling was by no means random. In addition, interviews were conducted via telephone, rather than in person.

A credible study would take a large, random sampling of people who have undergone Reparative Therapy, not just alleged successes. Interviews would be conducted in person, ideally with the use of a lie detector.

In addition, the standard scientific tests for attraction should be run. Different parts of the brain respond to sexual stimulation. Measuring brain activity in people who claim to have changed would be essential. Also, simple tests for physical arousal should be done.

I say all of this partly because I have long felt this and partly because of a 1996 study I heard about recently. A sampling of (allegedly) heterosexual men at a the University of Georgia were shown homoerotic films while attached to a device that measured genital stimulation. The men were interviewed beforehand and not told what sort of films they would be shown. The men who self-identified in the interviews as the most homophobic all reacted positively to the homoerotic films (i.e., they got boners). The men who said they had no problems with gays were not turned on by the films. Participants were interviewed again afterward. The men who identified as homophobic yet were aroused by the films lied and said they were not aroused. This despite having their pants around their ankles and being hooked up to equipment that measured their definite arousal!

Here's a short video on the study.

Another thing to consider: many ex-gay groups consider becoming celibate a "successful" change in orientation. This is completely ludicrous. The same-sex desire has neither changed nor diminished; rather, the individual simply stopped having sex with people of the same gender.

What do you mean by the psychological profession treating homosexuality as normal? I can't speak for Trinidad-Tobago but, here in the US, the psychological professional has regarded homosexuality as "normal" since it was removed from the list of mental disorders in 1973.

Science gives way to politics, yes, but the reverse of the way you see it. Science is ignored in favor of political posturing.

billy said...

I'm not sure how useful it is to talk of genes "determining" (or even "influencing") sexual orientation. The fact that there may be a slight correlation between certain patterns of genes and homosexuality tells us little. There are a huge number of steps between the expression of a particular gene and the manifestation of a particular sexual desire. Until we have a basic biological model for understanding human behaviour, a biological explanation of sexuality must be pure speculation. And we're not even close to that model.

Zee said...

Mr. HCI, just because they are not interested in showing you tolerance is not an excuse for intolerance. Doing the right thing should never be conditioned on others doing the right thing.

Mr. HCI, it is a valid comparison he made. I don't want to depreciate the struggles of trans people either. Also there is nothing wrong with religion thank you very much. If we found a medical way to change sexual orientation, I am sure the gay would be up in arms aganist it.

Mr. HCI, it all goes back to the idea of how you define sexual orientation vs sexual behavior. Gay and homosexual can be very subjective terms. Also like i said, homoerotic arousal does not mean homosexual. It is like saying that if you had heterosexual arousal, you are heterosexual.

Celibacy in itself is a whole different issue. From a religious point of view, many see celibacy as a proper course of action. Don't try to depreciate their lives either because celibate people have tons of hardships they had to overcome often live not fully accepted by any community. At least some community is willing to hear their story.

Aek said...

naturgesetz, billy: You're both correct, I apologize. "Determined" would not be the correct choice of words here, but rather "influence" or "affect" is more accurate. It's so easy to slip into the language often used by the lay media.

And billy, a biological model can get very complex. I doubt one will be elucidated in my lifetime. In my next post, I can show you just how complicated it can get, and yet it'd still be barely scratching the surface!

Mr. HCI, Zee, A. Friend: You all bring up very important points. A couple points I wish to address.

1. Handedness is a tricky thing. Many many people are conditioned against using their "originally dominant" hand to the point that it's no longer dominant. Does this represent a fundamental change or restructuring within the brain? I don't know.

2. I believe we can confidently say that it's very difficult to "truly" know if an ex-gay really has changed his/her sexual orientation. I don't know what goes on in their minds, and thus I cannot not know for certain. I will reserve (final) judgment.

3. Ex-gay propaganda certainly is dangerous in presenting misleading info, and garnering support for something that is likely completely erroneous.

4. The science of human behavior is a VERY difficult thing to assess. Even brain scans and arousal measurements can lie. It may be different across cultures. It may/may not be reproducible, a pillar of science.

5. Oh, asexuality is an orientation. So celibacy as a "success" might, in a twisted sense, BE a success for them.

Mr. HCI said...

Date:circa 1735

2 a: unwilling to grant equal freedom of expression especially in religious matters b: unwilling to grant or share social, political, or professional rights : bigoted

[defitions 1 and 3 are not related to the topic at hand]


Ex-gay groups have a right to make their claims, and I have a right to challenge them; that is not intolerance as I have made no assertion that they should be silenced. On the other hand, they want my civil rights restricted due to my sexual orientation, and that is pure intolerance (see 2b above).

I reiterate that sexual orientation and gender identity are separate issues. Psychological attempts can be made to change the former but not surgical ones. The latter can be physically changed surgically but not psychologically.

Sexual orientation and sexual behavior are indeed, different. Homosexuality, heterosexuality and bisexuality are all orientations; they describe what the individual finds sexually arousing. A person who is aroused by by the same sex and not the opposite is homosexual no matter how much straight sex that person has. Randy of Overrated Integrity, for example, has slept with 22 women but never gotten anything out of it other than physical release. He's now had sex with one man and confirmed to himself that he is definitely gay. From your statements, it would appear that you would say he is heterosexual because the vast majority of his experience is with the opposite sex. Please, correct me if I am misinterpreting you.

Please stop trying to put words in my mouth. I said nothing critical about people who have chosen to be celibate. All I said was some people make the claim to have changed their orientation when they have actually chosen to be celibate while still feeling same-sex attraction, thus making their claims of a change in orientation a false.

Mr. HCI said...

The above was in response to Zee. That sneaky Aek got in a response while I was writing it.


In response to point 5 in his invasive response: asexuality as an orientation means the individual has no sexual interest in anything. Vowing celibacy while still having sexual desire, be it hetero or homo, is not an example of asexuality.

Zee said...

HCI: I think the words you use (putting adjectives everywhere to place that doubt on their sexuality) does so some intolerance towards it.

Just because we have not tried to change sexual orientation yet through medicine doesn't mean we can't in the future. Why is it that one can feel trapped in the wrong gender but not in the wrong sexual orientation? Both make sense to me.

You misinterpreted what I was saying completely. I am saying most people aren't exclusively any sexual extreme so arousal to something proves nothing. If I get some arousal out of a naked female does it make me straight?

In response to celibacy, some can see it as a cure because it is a spiritual cure.

Aek said...

Mr. HCI: Well, how do we know that said ex-gay is merely "vowing" celibacy or "truly" celibate? Would it not be plausible (suspending suspicions) for an ex-gay to have no sexual desires for either gender rather than "converting" sexual desire from same-sex to opposite-sex?

Mike said...

The left handedness and gay thing is interesting. What determines hand preference? I dunno if that's a stupid question, but I'm curious.

Aek said...

Mike: I'm not sure that anyone truly knows what determines handedness, only that it's "set" by like, the 4th or 5th month in the womb (I think).

There's a higher likelihood of a child being left-handed if one (or both) of his/her parents are, but it's far from 100%. People think it follows an evolutionary concept called "frequency-dependent selection." It's really cool, though a bit difficult to describe.

All that said, handedness CAN be suppressed. In fact, left-handedness throughout history has been thought to be underestimated because many left-handed people were raised to use their right hands at a very early age. Because children's mind are so "plastic," the right hand becomes dominant and they're functionally right-handed.