Determining genetic influence on sexuality

This is a pre-emptive offshoot of the "turning gay" thread which looks like it might close soon (hit 300). The question people seem interested in (and I am) is evidence for genetic components of homosexuality.Tal has been raising questions, and so have I, about the nature of research in this area. Some have been very kind to be delivering info and discussion.Tal raised a question, which has some bearing on a question I raised as well. While the focus was on homosexuality, in essence this must bear on all sexuality. That is genes can't be said to simply account for gayness, but for the diversity of sexual orientations. Are we basically heterosexual with genetic mutations that allow for other sexualities, or basically trysexuals (we'll try anything) with genetics that might limit some to specific ranges with social environment playing the larger role in what any individual is?When looking at research data we need to keep those ideas in mind. Thinking heterosexuality is some base is not necessarily the correct model, as strict heteroism may very well be the mutation.Part of this is also defining what we mean by homosexuality or heterosexuality. Do we mean desire to have or ability to enjoy sex with a certain group, or do we mean the desire to have long meaningful relationships with a certain group to the exclusion of the other.I will use myself as an example here. In relationships I am hetero. I do not find men's faces attractive, nor do I feel any pull to get to know a man on a long term basis of caring. However I do like the look and feel of male genitals and so enjoy having sex with other men, in addition to having sex with women (who I do feel a "deeper" attraction to). Given that all research has to have self-identification of sexual orientation, what do I "count as"?The idea of anyone being singularly hetero or homo is itself new, and I believe, rather artificial. That is in addition to the difference between sexual interest and caring interest I noted above. How are people properly categorized in this genetic research?Okay, those were some opening ideas...(edited to remove potentially offensive wording)This message has been edited by holmes, 08-24-2005 07:01 AM

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

You might want to look at the Kinsey reports and any follow up research on the subject. As I recall (note, the genetics of sexuality are not even close to my research speciality), Kinsey struggled to develope a classification system that would define sexuality along a spectrum (1-5 scale) with 1 being extreme hetero and 5 extreme homosexual.Indiana University BloomingtonI will point out that in most genetic studies of behavior, defining the behavior is hugely problematic. For example, if you want to do a linkage study of schizophrenics, do you include the ones who hear voices? you can subdivide the trait a lot and each variant may have a different underlying genetic basis. It is much harder to define when dealing with non-pathologic behaviors...if I were a quantitative geneticist..I think I would stick to morphological characters.

Here is a link to a brief survey of animal homosexuality that some may want to review as background for this discussion.http://www.bidstrup.com/sodomy.htm

Before I respond, let me note that I did read the links you provided in the other thread. The wiki links discussion of genetic research is pretty much negative, and the study shown was pretty horribly flawed. I agreed with most of the criticisms and caveats and could add a few.I did not come away feeling better about the research. Thanks. It appears to me that the answers being sought here will only be answerable in this way (see what you think):1) Separating action from identity. Thus instead of identifying "gayness" or "straightness", identify interest in sex with same or opposite gender or both, and interest/attraction to form longterm relationships with same/opposite/both genders.2) Identifying physical brain structures related to those interests. Obviously even if it is choice based or nongenetic, there is still an actual physical part of the brain which is active when we "feel" our attraction, whether purely sexual, or emotional, or both.Could there be different areas activated when attracted to a woman instead of a man (regardless if which gender you are)? Or is it different based on attraction to same/opposite gender of yourself? Is it different when one is attracted "emotionally" rather than "physically"?3) Once we can identify the neurological basis, both drivers (making us feel) and receptors (allowing us to receive inputs to those areas), we can begin to look at what went in to shaping those neurological nets. Are they primarily genetic in origin, or influenced wholly by hormones, or perhaps they are in portions of the brain which can be shaped through social interaction... or the combination.

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

I think the latest Dean Hamer study is a better beginning of the analysis...but of note, his work from the 1993 Nature paper showing linkage to Xp28 was not reproducible. There is not a huge amount of study of the genetic basis of sexuality in humans in any case so I can see that it would be a bit of a disappointing read.Well, I have to go work on something else now so probably won't post til tomorrow...I am hoping Wounded King or mick or any of the other biologists might chime in on this subject since again, this is not my specialty...maybe Wounded King as a developmental biologist has more info.

Heheheh... well it doesn't exactly answer questions on how we should identify sexuality, but it does show the prevalence of diverse sexuality within nature, including a difference between longterm and short term sexual preferences.Interesting to note is that the Bonobos are identified as 100% bisexual. As they are our closest genetic relative, if we are to believe genes and sexuality are overtly related, I will note that this suggests our bias for natural hetero baseline in genetics could be flawed. Perhaps we should not be looking for a gay gene, but rather what gene(s) are present which allow for limitation to one gender as a sexual preference, rather than a natural openness. That could be for both hard straight and hard gay.

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

Well I don't know that I would go that far - however I do believe sexual orientation is a continuum rather than having discrete points of homo vs hetero. It is also possible that changes in sexual orientation could occur as we age. It has also been my suspicion that the most violently homophobic individuals are individuals who are unsure (and thus afraid of) their own sexuality. I don't have any evidence for this and it would not be easy evidence to get but how many times have we observed someone who is very anti-gay turning out to be a closet gay? That could also explain why lesbianism doesn't seem to evoke the same hate among "straight" men that gayness does - it is not really a threat to their sexuality.

Wouldn't the presence of a continuum within a world where most societies pressure people to be one sexual orientation, suggest a baseline bisexuality with social environmental pressures eventually forcing a person into a comfortable point everyone can identify?

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

Holmes, Can't you be a little more polite? That is a hideous way of phrasing it. I suggest you edit as follows: "I do not care for men's faces, but I do admire certain male accoutrements."Sounds much better.

I found the following review to be quite helpfull: Born gay? The psychobiology of human sexual orientation.The authors make several arguments that I found interesting. One, is that sexual orientation does seem to have real, emperical taxa underlying it - it's not just a semantic classification. Another is that it appears males have a more bimodal distribution - usually either heterosexual or homosexual - whereas women are more somewhere in between. Now that's obviously a generalisation, and there are going to be exceptions.This doesn't really deal with the issue of how to define sexuality though. It's a difficult question. It is important to distinguish between how a person feels and how they act - I believe orientation should be the feeling. But distinguishing between physical attraction and emotional attraction - I don't know. I suspect that for a lot of people (myself, anyway) the two go hand-in-hand. I only want an emotional relationship with people of the gender I am physically attracted to. That's pure conjecture on my part, and I don't know if any studies have looked at this.

I have to agree with deerbreh that the idea that a heterosexual baseline is not inappropriate. While there may be selective advantages to having homosexuals in the population, it is hard to imagine homosexuality is the baseline. How would traits be passed on? I would argue that although sexual orientation is continuous and not a discrete trait, there is still enormous pressure to reproduce (or at least there was in the past in humans when our population size was not so large). I think the question both biologically and socially is how bisexual is the overall population? I don't necessarily mean expressed physically since as you point out there is intense social pressure against this expression. But how many people are physically attracted at some point to the same sex? How often does Pan troglodytes (not bonobos) exhibit homosexual behaviors? Mice? Other species? The point is, until there is a baseline established for sexuality, it is harder to define the extremes and therefore, harder to identify the genetic components that underly the trait....like I said before, I rather work on quantitative genetics of morphological characteristics...behavior is a pain.

This is a cultural issue, and I apologize if my wording is offensive. I was trying to figure out what to use, and thought that was inoffensive while being specific. Perhaps that word is more offensive in your area, than "dick" or even "penis" is where I have been.In any case "male accoutrements" does not do what I am trying to say justice.I'll think of something else. I will note however that there are plenty of things people say around here that I find quite offensive, but just deal with the variety of expressions.

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

If we must choose a baseline from one of the extremes, then I agree hetero is the most appropriate and obvious baseline. Not only is there the problem of passing on the genes, but there would have to be a question as to why the baseline is only seen in 10% of the population. Absolutely agreed, though I might put it as "polymorphous perverse", and perhaps concentrate on activities and interests without asking for individual "identity", as we have also seen there appear to be "Phases" that people go through in their sexual interests.

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

It appears that most scientific knowledge is on a per pay basis. All I could get to is the abstract. I have to say I have some issues with statements in the abstract, but they could be more than addressed in the actual study.Could you paraphrase the nature of the study as well as the results so I can better understand what went into their statements?It seems to me (just from the abstract) that it could just as easily be related to genetics which make a person more likely to adhere to social norms, than forming actual sexual identity. I agree with this. I think in order to have a longterm emotional relationship sexual attraction will be necessary, however it is not the case that sexual relationships require emotional attraction, or wholesale physical attraction.Given that western culture for the last 2000 years has been obsessed with making sure sexual relationships be confined to monogamous marriages, and marking nonemotional sexual relationships as less worthy and illicit, it is not surprising that studies tend to identify sexual "identity" as some solid and permanent "identity" with greater connotations than merely potential sex partners.

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holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)

It is not an unreasonable suggestion. Anything having to do with behavior, particularly something as emotionally charged as sexual behavior, is going to have a large cultural component. However, I don't think we have enough hard evidence (again, very difficult to collect) to say - if I had to guess I would say it is a bimodal distribution with the peaks close to either end and the "homo" curve somewhat skewed toward the middle.