Blank slate when you want it that way

By Razib Khan | July 11, 2011 11:44 am

Tim Pawlenty debates Lady Gaga’s ‘Born This Way’ idea:

Gregory pressed, asking “Is being gay a choice?”

Pawlenty ultimately said, “I defer to the scientists in that regard.”

Again, Gregory pressed: “So you, you think it’s not a choice. … That you are, as Lady Gaga says, you’re born that way.”

Said Pawlenty: “There’s no scientific conclusion that it’s genetic. We don’t know that. So we don’t know to what extent, you know, it’s behavioral, and that’s something that’s been debated by scientists for a long time. But as I understand the science, there’s no current conclusion that it’s genetic.”


This is one issue where the American Left has a tendency to be on the side of the hereditarians. In contrast, the American Right emphasizes the plasticity of human behavior, and its amenability to cultural pressures and individual will and contingency. Transpose the structure of the arguments to male-female sex differences, and many of the basic elements would be preserved, but those espousing them would invert politically.

One issue which needs to be clarified is the distinction between something which is explainable by genetics, and something which is not explainable by genetics but may still have a biological basis. It does seem that homosexuality is only modestly heritable. That means that genetic variation can not explain all the population wide variation in sexual orientation. The correlation between identical twins on height is much tighter than when it comes to homosexuality.

Does that mean then that since so much of the variation in homosexuality is “environmental” it is amenable to change? Let’s focus on male homosexuals, as the heritability estimates for female homosexuals are so much lower. “Environment” in these heritability estimates means a lot of different things. It can include what we normally think of environment, socialization. But it can also include pre-natal and post-natal developmental randomness which induces unpredictable biological variability. Then there are the mysterious changes wrought by infection. Finally, even non-linear gene-gene interactions are often included in the “environmental” component. In other words, even if most of the variance in homosexual behavior can’t be explained by variance in genes, that doesn’t imply that a male who has a homosexual orientation at the age of 12 is going to be able to change that through behavioral therapy with any ease.

At the end of the day I doubt we’ll fine a “gay gene” in the near future. And without that, people like Tim Pawlenty will continue to take the stand they’re taking now. Revised upward heritability estimates wouldn’t change anything either, if people don’t want to believe that a behavior has a strong biological basis for ideological reasons, unless you can offer up a robust concrete genetic association they’ll keep denying in my experience.

But a bigger meta issue has to be “so what?” If homosexuality has a biological basis, then in the long term one can imagine that someone could devise a “cure” for it, just as they have claimed with today with talk therapy and what not. But that’s the long term. In the short run it does seem that if something is biological the naturalistic fallacy will loom large in our political debates.

  • Peter Ellis

    I like Dan Savage’s challenge – if Pawlenty (or anyone else) wants to prove that sexuality is a choice, why doesn’t he choose to be gay for a while? Just for a month or so, he can swap back after.

  • B.B.

    Attitudes toward homosexuality have also been found to be influenced by genetics, so us homophobes can also proclaim that we were “born this way”.

  • http://lyingeyes.blogspot.com ziel

    I like Dan Savage’s challenge – if Pawlenty (or anyone else) wants to prove that sexuality is a choice, why doesn’t he choose to be gay for a while? Just for a month or so, he can swap back after.

    I don’t get it. Does he mean because being gay would obviously be repulsive to a heterosexual and so it’s obviously not a choice? Or because a straight guy couldn’t successfully pull it off successfully and so it’s not a choice? Or…?

  • skatr

    I don’t see any particular error of understanding in Pawlenty’s answer.

  • DK

    One of the most straightforward, sensible and very easy to test explanations for [a large proportion of] homosexuality can be found here. I find it totally legit on every level, love the fact that it can be easily tested and I am awed by the fact that a non-biologist came up with this hypothesis. Now if only someone with sufficient funding looked seriously into it. In the first instance, a simple blood sample would be enough.

  • Darkseid

    you posted this great post on your pinboard feed a couple days ago:
    http://scienceblogs.com/gregladen/2011/07/how_do_you_get_sexual_orientat.php
    pretty much explains everything

  • gcochran

    In the spirit of Greg Laden, we must realize that homosexuality is most likely caused by an imbalance of bodily humors, perhaps caused by a toad or a small dwarf living in their stomachs.

  • chris

    “I like Dan Savage’s challenge – if Pawlenty (or anyone else) wants to prove that sexuality is a choice, why doesn’t he choose to be gay for a while? Just for a month or so, he can swap back after.”

    But people already have, it’s called prison.

  • http://entitledtoanopinion.wordpress.com TGGP

    Laden didn’t really seem to answer the question posed in the title.

  • Thomas

    @ DK
    Very interesting, thanks for the link. I’m really not qualified to judge this theory though. Anybody with better knowledge of the area like to comment?

  • Justin Giancola

    I also enjoyed DK’s link, as well as gcochran’s comment! humors…well played.

  • Darkseid

    Greg Cochran: “EVERYTHINGS caused by a virus! The world has yet to recognize my perpetually unsubstantiated, condescending genius!”

  • http://lyingeyes.blogspot.com ziel
  • http://lyingeyes.blogspot.com ziel

    From the above link: “The interesting thing about this is that a cursory examination of potential human gender diversity from a purely biological point of view suggests that there are at least dozens of “genders” but the vast majority of cultures define (or even allow) only a few.”

    What does he mean by multiple “genders” – strict monogamists vs. serial monogamists vs. cads vs. polygamists etc? Or homosexual vs metrosexual vs couch potatoes vs hard-drinkers vs wife-beaters?

  • DK

    Laden didn’t really seem to answer the question posed in the title.

    He never really does that.

  • toto

    Finally, even non-linear gene-gene interactions are often included in the “environmental” component.

    Wouldn’t that show up as a large difference between DZ and MZ twins though?

    Skatr: I don’t see any particular error of understanding in Pawlenty’s answer.

    The problem with Pawlenty and Gregory’s discussion is not what they say, but what they imply, i.e. that anything not genetic is necessarily a “choice”. One prime candidate for a homosexuality “cause” is hormonal balance in the mother’s womb. That’s not genetic, but that’s still biological – and that’s definitely not a choice.

    I liked Greg Laden’s post, precisely because it did a good job of explaining these points to an audience for whom they might not be obvious.

  • Connie Dobbs

    @bb(#2) yes, Homophobia is just as genetic as homosexuality, considering they’re the same thing.

  • cornflower

    Sounds like a play on an ideological Turing Test. Could a straight person like Pawlenty live the life of a gay person for a month, such that no one (relatively omniscient to the private life during that month) could tell the difference in talk or deed?

    Maybe a month might not be enough. Many gay persons have to live a life of heterosexuality, hiding it in some cases even from themselves… But then again, these are gay persons raised under a heavy cultural influence of being perceived as straight.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #18, there are ‘norm of reaction’ issues here. shift incentives enough you can overrule your biological predisposition. the prison example is a clear case.

  • Muffy

    as the heritability estimates for female homosexuals are so much lower

    Do you have a source for this claim? That’s not my understanding of the current state of evidence. Since women have been studied less than men in this regard, it’s hard to come to a conclusion. There a good overview of the available data here.

    this discusses the male vs. female differences. Importantly, the famous Bailey, Pillard et al study did not find homosexuality less heritable in women than men. Kirk et al (2000) found that homosexuality is more, rather than less, heritable in females than males (see here).

  • Clark

    It always struck me that the way the debate is cast is just plain weird. Of course it’s all biological – what else could it be? The very choice vs. biology opposition some people raise is just strange to me.

    I think what people want to say is whether there’s some easy way to stop. But the way they put it is quite odd. (I’d note that something similar happens in the debate about addictions – if one can’t just decide to stop it must be an addiction)

    Ultimately the real problem is that people’s idea of biology is just woefully bad. I like the reference to Pinker’s Blank Slate in your post title. It was a pretty flawed book but the basic thesis was correct I think. Some old ideas from the dawn of modernism still dominate how we think about human behavior despite being falsified long ago.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    Do you have a source for this claim? That’s not my understanding of the current state of evidence. Since women have been studied less than men in this regard, it’s hard to come to a conclusion. There a good overview of the available data here.

    1) i do provide links for that very reason :-) so, at the wikipedia article the citations leads to: Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden:
    There is still uncertainty about the relative importance of genes and environments on human sexual orientation. One reason is that previous studies employed self-selected, opportunistic, or small population-based samples. We used data from a truly population-based 2005–2006 survey of all adult twins (20–47 years) in Sweden to conduct the largest twin study of same-sex sexual behavior attempted so far. We performed biometric modeling with data on any and total number of lifetime same-sex sexual partners, respectively. The analyses were conducted separately by sex. Twin resemblance was moderate for the 3,826 studied monozygotic and dizygotic same-sex twin pairs. Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance, the shared environment .00, and the individual-specific environment .61–.66 of the variance. Corresponding estimates among women were .18–.19 for genetic factors, .16–.17 for shared environmental, and 64–.66 for unique environmental factors. Although wide confidence intervals suggest cautious interpretation, the results are consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior.

    2010 paper.

    2) i’m frankly just suspicious of claims of female homosexuality heritability estimates in general before i see really clear ways of how they define lesbianism. many more avowed straight women seem to have a “lesbian” phase than straight men who have a “gay” phase :-) in fact, i’ve never met a straight man who thought he was gay at some point in the past, and realized he wasn’t. i’ve known of men who have experimented with bisexuality, more or less.

  • erica

    I didn’t see the interview, but in just reading Pawlenty’s words, I can at least give him kudos for not making blanket statements about this.

    So far, no genes have been identified because there aren’t any (yeah, I know, some claim it’s a complex polygenic trait); some claim it’s all hormones in utero, but even if that’s so, they haven’t answered what in the world is affecting 2-4% of women’s male babies in the womb to come out, by today’s standards, sterile (and by yesterday’s standards sub-fit since there is no way imaginable I can believe a truly homosexual man who married had as many offspring as his heterosexual gene competitors); and, if there is some kind of pathogen involved in triggering it all, it stands to reason that its effects could happen before birth but wouldn’t have to since there are strong neonatal hormone bursts, since the brain keeps developing after birth, and since brain cells can be attacked at any time like any other cells.

    All in all, I thought Pawlenty did just fine. Science hasn’t solved this riddle yet, and he makes clear that he knows that. Similarly, he seems to know that no gay genes have been identified which is a heck of a lot better than many of my progressive and supposedly well-educated friends who recall years ago that ” a gay gene was identified” and are surprised when I tell them that this isn’t so.

    Yeah, the point about biological versus genetic is well-taken, but face it, the biological cause is still vague/unknown. If a Bill Clinton or a Barrack Obama had said, “I do believe people are born this way, that their genes have given them a homosexual orientation” they’d be no more “right” based on what we do and do not know, than is a Pawlenty.

  • Muffy

    Alright, thanks for the citation. It sounds like more or less the opposite conclusion of the Kirk et al study. In other words, it doesn’t sound like there is consistent data on the topic, one way or another.

    I do agree that self-identiy is a problem in women, although I’m not sure it’s any better for men. For every hetero woman who claims to be lesbian or bi too be chique, there’s a non-hetero man who won’t self-identify as gay or bi because it’s “gross” or something.

    Also, has it occurred to any researchers to use the Kinsey scale to measure sexual orientation instead of just “gay” or “straight”?

  • Grey

    “One of the most straightforward, sensible and very easy to test explanations for [a large proportion of] homosexuality can be found here”

    http://www.welmer.org/2008/07/14/the-chimera-hypothesis-homosexuality-and-plural-pregnancy/

    Interesting theory.

    http://en.wikipedia.org/wiki/Freemartin

    The things you learn when you follow links.

  • http://theunsilencedscience.blogspot.com/ nooffensebut

    i’m frankly just suspicious of claims of female homosexuality heritability estimates in general before i see really clear ways of how they define lesbianism

    A few years ago, I created a popular YouTube video that summarized the case that lesbianism, unlike male homosexuality, is not biologically driven. Then, I discovered a study that produced a high heritability estimate for women who sometimes engage in lesbians behaviors. I think anyone who is trying to invent a Viagra for women must believe that female sexuality is more complex than male sexuality. So, why isn’t a personality dimension incorporated into these kinds of discussions? It seems to me that male sexuality, like aggression, should be regarded as relatively elemental, whereas lesbianism should be regarded as a symptom of a personality profile that has a meaningful genetic component.

  • Justin Giancola

    What of the greeks, romans, japanese, celts of antiquity? Typically among men of power. Or SA Nazi’s of modern times? To probably name just a few. That was elemental, no personality profile?

  • Darkseid

    is it not just de novo mutations. like everything else is likely to be. or am i way off?

  • gcochran

    You’re way off. If homosexuality were caused in large part by de novo mutations, a noticeable fraction would be syndromic – that is, cause other noticeable phenotypic effects. Like Waardenburg syndrome, deafness and a white streak in the hair. Or fragile X: big ears and macroorchidism. More generally, retardation and funny-looking kids. I don’t think has ever noticed anything like that in homosexuals.

    Moreover, sexual interest is surely not as complicated as, say, hearing or vision, and thus should be a smaller mutational target – which implies that homosexuality should be rarer than blindness or deafness. But it’s much more common than genetic congenital deafness, which hits about 1 in 1500 kids.

    That said, it is entirely possible than some small, maybe tiny fraction of homosexuality _is_ due to de novo mutations, and if anyone found such as a case, we could learn a lot from it. As we did with narcolepsy, in dogs.

  • Darkseid

    ok, thanks for the response Greg.

  • http://wiringthebrain.blogspot.com kjmtchl

    Just because something is not entirely heritable does not mean it could not be entirely innate. Handedness is a good example – it is only partially heritable (people are more likely to be left-handed if one or both of their parents are, but even with two left-handed parents the chance is only about 30%) – but there is no evidence that the trait is affected by environmental influences (i.e., from outside the organism). What seems more likely is that genetics affects the probability of neural development following one trajectory or another and ending in one state or another, but the final outcome is also influenced by intrinsic, stochastic events during the incredibly complicated processes of neural development.

    For more on this in relation to sexual orientation in particular, see:

    http://wiringthebrain.blogspot.com/2010/07/sexual-orientation-wired-that-way.html

    http://wiringthebrain.blogspot.com/2010/05/sexual-orientation-in-genes.html

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About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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