Several new twin studies have been published over the past several months. A new one, just published on the Archives of Sexual Behavior website, deals with sexual orientation and neuroticism and psychoticism (more about that study in a future post). One of the co-authors of this new paper is J. Michael Bailey. Dr. Bailey is among the world’s top sexuality researchers and author of numerous publications involving twins and sexual orientation. Here he comments on the limitations of twin studies and sexual orientation change. This conversation was triggered in part by the recent NARTH report which stated that “homosexuality is not innate” without research supporting the statement.
In an email, I asked Michael to discuss how both the right and left misunderstand twin studies and their relationship to questions of innateness. His answers are indented and presented in full with some comments from me.
Both the left and the right conflate “genetic” with “inborn.” The debate over sexual orientation (and other traits) is more about inborn than genetic. As an example of the difference, it is common for identical twins to be discordant for homosexuality (i.e., given a gay identical twin, his twin is usually straight). It is a terrible mistake, though, to assume that this reflects the kind of social environment that can be manipulated. As you know, childhood gender nonconformity is very highly predictive of adult homosexual outcome. I’ve spoken to several mothers of identical twins discordant for
extreme childhood gender nonconformity (where one male twin wants to be a girl and the other is a typical boy). In each and every case, the mothers insist they did nothing–nothing–to differentiate the twins until well after the behavioral/emotional differences emerged. I
believe them.
On this point, some observers might not be quite as believing as Dr. Bailey. However, I lean in his direction on this, especially with extreme gender nonconformity. On this blog, we had an extensive conversation with a mother of twins, one quite non-conforming and the other not. In this context, it might be good to review those posts. (part 1, part 2). At the same time, I am aware of some parents who do indeed raise kids to prefer gender nonconformity. Extremes in childrearing may in some cases influence the trait of gender nonconformity in kids, but one does not need such parenting to get the same result.
The left often assumes some genetic influence means that social environment plays no role at the individual level. If some genetic factors operate for some, then they must operate for all. However, this cannot be assumed from twin studies. Neither can it be assumed that the differences between twins all relate to environmental factors which are alterable. On this point, Bailey says:
The main issue is nature-nurture. Heritability (which can be estimated from twin studies) generally is consistent with nature. But environmentality (the complement of heritability) DOES NOT MEAN nurture as it is typically assumed (i.e., social and reversible causation). MZ twins [monozygotic or identical] can differ (and I expect usually do) for biological reasons. At this point neither hypothesis (biological or social causation of MZ twin differences) has strong evidence to for it.
Note the last statement. We simply don’t know as yet. This is another reason why I think why I believe the NARTH paper is misleading. The paper uses weak therapy research to make a statement about innateness and immutability of sexual orientation. First we do not know whether twin differences occur for social or biological reasons. And then we do not know if any of the factors in any given case are alterable. Francis Collins made this same point when reacting to how Dean Byrd at NARTH quoted his book The Language of God:
The evidence we have at present strongly supports the proposition that there are hereditary factors in male homosexuality — the observation that an identical twin of a male homosexual has approximately a 20% likelihood of also being gay points to this conclusion, since that is 10 times the population incidence. But the fact that the answer is not 100% also suggests that other factors besides DNA must be involved. That certainly doesn’t imply, however, that those other undefined factors are inherently alterable.
The recent NARTH paper implies that studies demonstrating some shifts in sexual behavior disconfirm the view that homosexuality is innate. As Bailey notes above, we do not know. However, Bailey indicates a situation which provides a problem for environmental hypotheses.
Studies of the rare conditions of penile ablation and cloacal exstrophy (in which hormonally normal males are reassigned and reared as females from a very early age) show that such males grow up to be attracted to females, as per their biological, but not their social sex. To repeat something I’ve said many many times (and have never had a good answer), if you can’t make a male attracted to other males by cutting off his penis and rearing him as a female, how likely is any social hypothesis?
Bailey adds a bit of a challenge to his comments:
The folks who insist that (male) sexual orientation can be changed should put their money where their mouths are and fund you and me (and the researcher of their choice) to do a study with objective (i.e., penile and neural) pre-post measures.
We have discussed a study like this since 2006. I am aware of people who would participate but funding is an issue. Bailey and I both have sought such funding but no one has provided encouragement.
Anyone interested?
I will have more on the NARTH paper in future posts. Thanks to Michael for his comments and expertise.
@Warren,
1. I should have read more carefully. Yes, I see now that it was Collins who used the 20% concordance for twins. (I believe the most reputable studies have placed those MZ twin concordance rates at 25%-30%.)
However, my point about Bailey is that he speaks of “heritability”–and I still wonder how or if they have actually established that twin concordance rates for SSA (whatever those rates are ) are evidence of genetic heritability as opposed to biological factors. (Again, perhaps the Sanders/Bailey gene study will help clarify this.) That was the crux of my question.
2. Thanks for the link. I should have mentioned that I did know the results of the study. It has been criticized for its sample (internet responders) and as not really establishing much but praised as offering an interesting line of inquiry for further study.
There have been many who have suggested HLA typing might tell researchers something. I guess that is very expensive? Since Bailey’s major research subject seems to be the etiology of SSA, I wondered if he or Sanders (or anyone else with whom they collaborated) had done blood or HLA tests.
I think this huge DNA study Sanders/Bailey got money for only asked for cheek swabs to collect DNA. Unfortunately, if that is the case, it seems they wasted a great chance for other tests. Yes, I suppose they were limited by money. If they get another grant, they might be able to use the same test subjects for further tests.
Evan: “Maybe they love football players, I don’t know, but there should be a proportion who actually are into sports. Usually, their interests are in the arts, fashion, body care or intellectual area.”
WOW! Play into stereotypes much at all?
Pathia — My opinion is that sexual orientation is not supported by a special, dedicated or separate system in the brain, but it uses a number of components of the emotional brain which manage stress, aggressiveness, emotional memory and evaluation of emotionally salient stimuli. Some of them seem to play a pivotal role, especially those involved in stress and aggressiveness. So, yes, playing football or doing any other activity that keeps someone nurturing more assertiveness during their childhood is likely to influence how they will be positioned in terms of gender typicality and future sexual orientation. On the other hand, not doing so and growing up with girls and/or taunted, rejected by peers or other masculine figures, may influence their stress patterns, their lower levels of aggressiveness, their emotional impressionability, how they react to shaming situations, etc. The question is how much of this stuff is programmed by genetic and biological givens and how much flexibility is downward or upward.
Maybe they love football players, I don’t know, but there should be a proportion who actually are into sports. Usually, their interests are in the arts, fashion, body care or intellectual area.
Evan: Sorry, I just can’t believe because someone doesn’t like football and they get teased, that makes them gay. Nevermind the fact the kids that tease you for not playing football tease and brutalize EVERYONE, not just kids that may be a little more shy/reserved/less masculine.
Pretty much every gay man I know loves football! Your theories and ideas simply don’t mesh with anything I’ve observed in reality.
@Pathia
Many men who are predominantly SSA report having been taunted and rejected as kids, for instance for not playing football. But I suspect, in some, stressful events wouldn’t be so obvious and therefore they wouldn’t be recalled in connection with sexual identity development (childhood trauma can pass unnoticed or not remembered). What I’m saying is that vulnerable kids go through stressful events or aggressive environments differently than the rest. This might be primarily because of their genetic/hormonal background, but I wonder how much of their adult orientation is a result of them being rejected and growing up apart from their more typical peers. The brain is very plastic at that age and many factors could influence its development. The case of identical twins discordant for sex atypicality sticks out, either as a product of different womb hormones exposure or unique post-natal factors. It’s the unique factors that might be more important for boys who grow up in a typical way, but end up attracted to their own gender in adult age. That was your question, right?
Evan: There are still huge numbers of men who do not report ‘trauma’ in their youth at any level. Warren’s linked to studies indicating this recently. How do you explain normal acting boys, who had relatively normal childhoods, with not trauma or abuse, end up being gay anyway?
carole – it was Collins who said that about the 20% and I suspect he was writing for a lay audience and was specifically referring to twin studies.
Michael is more accurate to refer to biological factors which may or may not be genetic.
RE: Blood type – Yes – http://www.springerlink.com/content/g15680h356758417/
Pathia
It might be different for different people. Like genetics playing a greater role in some and a smaller one in others. I’m saying that it’s not necessarily evident that it must be only one factor in all cases. The case of men who weren’t sex-atypical when they were boys, but still develop as same-sex attracted men to some degree seems to argue in favour of something other than sex atypical genetic influences on development.
@ Warren,
Thanks for the clarification.
Two additional things–if you should get a chance to correspond with Mike Bailey again:
Bailey says that the 20% concordance figure strongly suggests that there are “hereditary factors” and then of course he goes on to say that this figure also suggests that because the concordance is not 100% there must be other factors other than DNA involved.
1) I was wondering why he chooses the word “genetic” to account for the 20% concordance since things like shared womb events would be more accurately termed “biological.”
I am certainly not arguing the point–just wanted clarification. (That is why I wondered if he “knew” something of the gene study, btw because concordance for things with twins can be shaped by biological events that may or may not be related to genetics.)
2. Can you find out if he knows if any study of SSA/OSA has ever investigated blood types and especially HLA types?
Thanks
Evan: If you believe my belief that genetics had something something to do with my orientation, than why does that not apply to others? If my system going awry in my birth/brain before birth cause it, than how does that disqualify that it can’t happen in non-intersex folks?
If I can have my identity and orientation scrambled by my genetic birth condition, doesn’t that innately mean that it’s from that time period and thus could be for others?
@Pathia
I remember you said you are bisexual and transgender and that you ascribe that to an intersex condition. Correct me if I’m wrong, but maybe your case is different from that of gay men.
Evan:
I can’t believe a theory like that, because I lived in a more or less perfect two parent family situation. I had no emotional trauma (Until the repairative therapy). My parents were loving, caring and brought me up no different than any other little boy, I simply acted different from birth. They noticed ‘oddities’before I could even SPEAK in my play habits.
How can you have emotional damaging experiences before you can even speak?
Thanks, Pathia.
This partly answers the first part of my question. But, to be honest, I was generally interested in how valid is this statement: if rearing a male as a female doesn’t change his sexual attractions then a social paradigm is not likely to play a significant role. This example conflates two different things: gender identity and sexual orientation.
I think this example is not satisfactory, because it assumes as a null hypothesis the proposition that the only way a man’s brain would be impacted to create a sex-atypical pattern of attractions relative to one’s inborn sex is by social learning of gender (assuming that the person would not have already been born with a predisposition towards sex atypicality.) I think there can be other ways than making changes in gender roles through which social experiences could lead to a sex atypical brain development. Considering that women show across many studies a greater vulnerability to stress and that a similar pattern has been found in gay men, I wonder if men with particular genetic and/or biological predispositions who undergo traumatic levels of stress during early brain development could not develop same-gender attractions as a result of environmental stressors. Many gay men have reported being taunted or rejected as kids and I think scientific studies should consider the degree to which this could contribute to their adult brain configurations.
If their findings from the 2007 brainscanning study that the only group difference between straight and gay men is a greater activation of a component of the stress system in gay men are replicated, then this possibility must be considered instead of this extreme case involving premeditated learning of cross-gender roles.
Another possible explanation of their findings is that it’s not only the difference that matters, but both the difference and the similitude. Considering Savic’s PET rCBF findings from last year, showing sex-atypical connectivity in gay men and lesbians amygdalae, it can be argued that the findings from the Bailey lab were also due to different processing leading to similar arousal. The question is if these patterns were the result of early stressful experiences that led to formation of sex atypical structures or if they were put in place by pre-natal factors, or both. This is why I think the extreme example with cloacal exstrophy and social learning of gender is not convincingly related to a sex atypical development of gay men’s brains.
Evan:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1421517
Studies have been done, they tend to switch back to male in a majority of cases it seems. Not all, but 8 out of 14 declared themselves male and this is a study of them before they even turn 18. I suspect it would go higher later you go.
Carole – Got it confirmed from Michael that the study is not at the printer. Data are still being analyzed…
To repeat something I’ve said many many times (and have never had a good answer), if you can’t make a male attracted to other males by cutting off his penis and rearing him as a female, how likely is any social hypothesis?
——————————————————————–
This struck me.
I remember a documentary about the Dominican Republic and how they have an unusually high number of hermaphrodites (if I can remember correctly). They profiled one “guy” who was raised as a girl and who just decided to abandon it and date women when he got older.
I didn’t know there was research on unambiguous boys being raised as girls however. I hope you can talk about that sometime in the future because this is an interesting point.
Dr Bailey —
Forget about the question.
Dr Bailey said:
There might be a problem with this example. Since cloacal exstrophy is a very rare birth defect, one would need a very large sample of men with such a defect to have an equally representative sample that would reflect the population distribution in terms of sexual orientation. A few cases of cloacal exstrophy cannot prove without any doubt that a proportion of the population may not be more vulnerable to some post-natal environmental factors that would impinge on brain development and thus on their future sexual orientation. A few cases in which men would be reassigned a female sex and be reared as females without developing a heterosexual orientation relative to their reassigned sex may be due to particular genetic and biological data that would place them in the highly masculinised part of the spectrum, and thus make them less vulnerable to experiential factors.
Secondly, female rearing may only involve social learning of gender roles, which would not necessarily affect brain development to the extent that it would create sex-atypical adult orientation relative to birth sex. Does rearing a man as a female imply subjecting the person to high levels of stress (traumatic or not) that could lead to a sex-atypical development of certain brain regions also involved in sexual arousal (eg, the amygdala)?
If so, do particular individuals react differently to stress and therefore, as a result of different developmental experiences could end up on different trajectories with respect to their sexual orientation?
From Mr. Bailey:
From Warren:
I highlighted those words. “We simply don’t know as yet”. This is nothing new for NARTH. I noticed NARTH’s “misleading” tendency — while I was still actively ex-gay. That’s why we (EXODUS) never affiliated with NARTH.
We were approached. We said no. Or more accurately, I said no, because I was the only one of the “founders” who had taken a research/design class. I saw the errors. The same types of errors we were being taught not to make. I got an “A” in the class. I honestly don’t think Nicolosi would have.
I was a young student and as a new Christian, I really wanted to believe gays could “change”. It would have been really nice if we could find some good, solid, reputable evidence.
So, we looked at NARTH — and NARTH already came across as very “unscientific”. Nicolosi struck me as a quack with an axe to grind — not a real scientist. (That impression remains.)
I was working on my Master’s degree and the research/design class I was taking made me very uncomfortable with NARTH’s motives and methods. Even back then, it just didn’t seem like good science, for these reasons:
(1) They frequently stated theories as though they were established facts (Reification of the Construct).
(2) They frequently engaged in “post hoc, ergo propter hoc” reasoning — confusing correlation with causation. I wondered then — and still wonder — if they did it on purpose.
(3) They made sweeping generalizations based on inadequate evidence. They seemed to be saying, “We have already made up our minds — but here is something that sort of agrees with us” — but the studies did not really warrant NARTH’s conclusions.
“Weak research” was then — and still is — NARTH’s biggest problem.
Sorry…. all my savings went to my health care.
Okay, thanks.
I thought all they were now doing was sending it to be printed.
Carole – I will let Michael speak for himself if he wants to comment but I don’t think one can take anything about the Sanders study from his statement here. I do not think that analysis is complete as yet.
Warren,
Well, guess that tells me that the Sanders/Bailey Northwestern genetic sequencing study of twins, the results of which have not yet been released, didn’t establish genetic linkage to Hamer’s Xq28 or at least not enough of one to explain Bailey’s comments here.