How can gayness have a genetic basis?

[Phil153]

[ QUOTE ]
Phil, I don't want to get too far off track, but based on our discussions the above statements seem very much at odds with your views on neurobiology and human behavior. For example, I'm very interested in why you attribute a big role for environmental influences in development of sexual attraction and none (or close to it) for intelligence, brain size, etc.

[/ QUOTE ]
Hey RDuke,

Firstly, I apologize for the length of this. I know you're a busy man but brevity isn't my strong point.

Regarding intelligence and biology: they're too different beasts. I'll tackle sexual preferences first. People have sex:

- Because they get horny when around specific triggers
- To feel powerful
- To feel loved/included/meaningful
- To scratch an itch
- For emotional/physical intimacy with a person
- To relieve boredom
- Because it's familiar way to gain pleasure

These things vary greatly from person to person. For example, some gays like to bottom, because they like the feeling of being dominated and being someone's "cumslut". That site I linked earlier that you deleted had plenty of that kind of discussion. Some straight males only have sex with women for power and the itch scratching. Some emo males have a naturally low libido and only do it feel loved. So you can see that these reasons are varied, and to present the dichotomy of "being gay" or "being straight" is kind of ridiculous. I've talked to a lot of gay people, and I know that many of them:

- [censored] purely for pleasure, for their respect of another man and wanting to be part of his coolness.
- Are scared of women
- Feel comfort and brotherhood with men, and most naturally form a relationship with them. Women seem like foreign creatures to them when it comes to intimacy.
- Are seeking novelty and experimentation
- Are brain or drug damaged or affection starved as children, and have problems with normal boundaries (in the clinical sense).
- Are self loathers who feel they deserve to do dirty stuff (some former Catholic molestation victims fit into this).
- Like a specific man's skin/hair/eyes/smile/voice/power, and get captivated and turned on by that specific trait, end up having some of their first sexual experiences with this person, and the preference gets wired in. This is similar to the fetish response that I talked about earlier.

I think where there is a predisposition for gayness, it's due to the way underlying personality traits (NOT a "gay gene") interact with social experience, to produce all kinds of sexual preferences which span the range of those listed, and more. Humans are also generally risk averse and creatures of habit, and are strongly influenced by friends, culture, and defining childhood experiences. University is a great place to see this - ask someone what first motivated them to follow their career path, and it's often a hero of some kind, a single experience or observation that occurred in childhood, or a continuance of what they know through their family. We're idealistic creatures, especially during younger years when the brain is forming and sexual preferences are getting wired in. Finally, if you look at what can and does go wrong with developing teenage brains, it shouldn't be any surprise that some will get wired into a odd fetish-like preferences.

So what I'm getting at is that even if everyone was born straight, some percentage would ultimately fall into an alternative lifestyle. We're uniquely capable of overriding and not recognizing our basic urges, and doing things for reasons that have little have to do with programming or biology. Simple crossed wiring and various kinds of personality and preference development in the young brain are adequate to explain gays and lesbians, in my opinion.

As for the intelligence bit, and the fact that there is evidence of a prenatal component, I need to go a bit deeper to explain what I mean.

I'm pretty sure, based on a no research at all, that many basic behavioral traits are the result of natural differences, such slightly differing brain structures, hormones, cellular energy levels, and so on. I think these things are responsible for much of basic personality. Examples would be reflectiveness, creativity, pleasure seeking, risk seeking, novelty seeking, libido, self control/willpower/stubbornness, degree of empathy, degree of emotional capacity, strength of emotional experience.
I think many of these things we call personality traits are properties of the mind itself - the sizes/neuron densities/connection qualities of various parts of the brain, the fineness of differentiation, the speed at which connections degrade, the repetitions required to build strong conduits, the natural levels of various neurotransmitters, and so on.

This isn't taking away from the fact that the brain is hugely malleable - far more than most think. But I think certain clusters of these traits will lead to a susceptibility to certain behaviors. It's something that's repeated in animal behavior and I think stands up, at least in every day observation.

I was going to write my thoughts on why intelligence is different - but this post is too long already and I don't want to hijack. I'll do it later. [img]/images/graemlins/smile.gif[/img]

[Subfallen]

Phil -

I'm not particularly bisexual, and will be quite content to die without f'ing or sucking another man. But I can still imagine having an encounter with some sexy, brilliant guy after a bit of desensitisation. (Ok, I'm having too much fun with this.) On the other hand, I cannot imagine not wanting to [censored] women.

So...my point is this: isn't the necessary condition for "gay" really that one is NOT attracted to women? This genuine absence in some men IMO is much harder to explain via neurological malleability.

[Rduke55]

I don't think you answered my question.

Is there plasticity in sexual attraction? Sure. Certainly I like certain aspects of the female form, clothing, etc. because of environmental influences.
I think that the subtleties of attraction are very much due to environment (attraction to breasts, dominance, fetishes, etc.) - I think you often conflate this with gender attraction.
Why do you see similar incidences of homosexuality across cultures, why do some animals perform homosexual acts, why can you get animals to court the same sex by manipulation (see mosaic brains in fruit flies for example), etc. if there isn't a genetic component?

What I'm asking is why you think that something as ancient, fairly cut and dried in both behavior and neural substrate (at least when compared to other traits), and with such massive selective weight as sexual attraction is left up to environment while something like variations in abstract intelligence, problem solving, etc. which are much more recent and unique, subtle, more malleable, and with far less weight is clearly genetic.

You are going against the majority of neuroscientists here. It's thought that gender preference is genetic to a large degree and variations in higher cognition has an enormous non-genetic component (epigenetic changes, nutrition, enrichment, etc.). I just want some insight into why you think the opposite of the field.

[Phil153]

[ QUOTE ]
Why do you see similar incidences of homosexuality across cultures

[/ QUOTE ]
Why do you see similar instances of any mental disease across cultures? Are they all largely genetic?
[ QUOTE ]
why do some animals perform homosexual acts

[/ QUOTE ]
Animals are wired to mount and penetrate other animals, and to get themselves off. Animals also perform inter species sex with suprising regularity, both domestically and in the wild (moose/horse for example). Do genetics code for inter species sex as well? Or is it simply a mechanism that causes desire for copulation and penetration with something that loosely fits sexual criteria?

[ QUOTE ]
with such massive selective weight as sexual attraction is left up to environment

[/ QUOTE ]
It's obviously not left up to the environment. The desire to copulate is extremely powerful. As is the human desire for social interaction and their almost instinctive susceptibility to social influence. Could encoding that normally causes female attraction be miswired in some cases? Sure. But humans are higher creatures driven in large part by social and emotional experiences built on the basis of various general tendencies. I basically think that the desire to copulate + the desire for various social ends results in gay behavior.

I guess what I'm saying is: I don't think it's likely that gays are specifically wired to want to copulate with males. I have no evidence for this assertion and am at a disadvantage debating a well educated expert in this field. If you tell me that they have found specific wiring that produces the desire for male copulation, then I'll believe you. However, I do think it's possible that traits for female attraction are miswired in some gays. If male bonding behavior is somehow wired into the brain, it's possible that problems in this area could become conflated with encoding for sexual urges and behavior. I'm not ruling that out.

My second, separate contention is that the majority of those identified as gays do it as a learnt behavior, so that claiming a genetic basis for these individuals is wrong. The prevalence of true, no female contact homosexuality is 1-3%, and lags behind the prevalence of regular bisexuality and well behind same sex experimentation.

[ QUOTE ]
while something like variations in abstract intelligence, problem solving, etc. which are much more recent and unique, subtle, more malleable, and with far less weight is clearly genetic.

[/ QUOTE ]
I have no hard evidence for this belief, but it seems to me that human brains have few specific traits, and many general ones. It makes a lot of sense to me that (1) people generally reach their intelligence potential, in the same way that most reach their growth potential and (2) intelligence is largely limited by hardware - brain damage, drug damage and aging lend support to that view. And (3) hardware is largely inherited.

You'll have a hard time convincing me that cultural differences are the reason that poor, short Chinese (and probably short partly through malnutrition, according to the latest research) destroy relatively wealthy, larger sub Saharan African descendants in tests of intelligence, especially when those same Chinese score the same as the inhabitants of the most advanced and educated civilization on earth, Japan, with which they share a recent gene pool.

BTW I've been a lot of reading of actual papers on intelligence. My conclusions so far are that:

- this area is horribly politicized - you can't trust anyone's conclusions or data, on either side, even when printed in journals
- psychologists and anthropologists have a poor understanding of science and logic and little in the way of intellectual ethics
- the only way to make any kind of determination is to look at the raw data, and probably collect your own.

At this stage I agree that the evidence does not strongly support my contention of a largely genetic basis, but it's far from conclusive.

[foal]

[ QUOTE ]
[ QUOTE ]
Why do you see similar incidences of homosexuality across cultures

[/ QUOTE ]
Why do you see similar instances of any mental disease across cultures? Are they all largely genetic?

[/ QUOTE ]
I'd say most have a sizable genetic component. Genetic predisposition, you could call it.
Some psychological disorders are culture specific (e.g. taijin kyofusho in Japan and Korea).

[CrayZee]

One last digression, I could very well be wrong on everything said in this thread as this stuff is not my forte...but one that bugs me is the whole notion of static, discrete sexuality. I suppose continuous vs. discrete is a statement of granularity, but this stuff does seem at least somewhat dynamic (something akin to a "bounded freedom of choice").

Most people won't make out with the same sex but it's certainly not a clear-cut, black and white issue.

[foal]

Very true, Kinsey believed everyone was at least a small "percent" bisexual.

[Praxising]

Geneotype + environment = phenotype. Phenotype is what we actually are, not some gene program. Your genes might make you six feet tall, your diet might make you 5'10." That's phenotype. Works the same with psychology and behavior and so forth.

And, phenotype is elastic, as someone pointed out, sexuality and gender are part of a spectrum, and the individual can move along that spectrum, just as you may be 5'10" when you are eighteen, have an increase in nutritional quality and quantity and be 6'1" by age 20, and shrink up to 5'8" by 80.

You all might want to recall for the genetic part of the discussion, that complex traits like gender preference are not a function of a single locus, but are influenced by gene complexes.

There was an interesting bit of research published, I think in the last year or so, about how the mother's body may affect fetal development and result in a gay individual. It was a study that found that most gay men were younger siblings, and the probability of being born gay increased with every male older sib.

I bet you could Google it.

[Phil153]

OK, a few things.

Everyone knows about the phenotype-genotype scale. We're beyond that.

[ QUOTE ]
You all might want to recall for the genetic part of the discussion, that complex traits like gender preference are not a function of a single locus, but are influenced by gene complexes.

[/ QUOTE ]
Really? We know which genes encode gender preference and how they work?
Or is it possible that the genetic basis of gender preference is a function of other traits clustering together?

[ QUOTE ]
There was an interesting bit of research published, I think in the last year or so, about how the mother's body may affect fetal development and result in a gay individual.

[/ QUOTE ]
Speculation. It seems reasonable, but it's far from settled. Let's not allow the fact of publication to blur the fact that this was one individual's speculation.

[ QUOTE ]
It was a study that found that most gay men were younger siblings, and the probability of being born gay increased with every male older sib.

[/ QUOTE ]
No, the probability of manifesting same-sex interest in adulthood increased with every older male sibling. They've merely speculated that this is due to influences in the womb. However, I can very easily see how having a number of older brothers could increase the incidence of crossed wiring between sex/affection/respect and the development of effeminate traits.

[All-In Flynn]

For sure. Really my whole interest in this concerns the possible genetic basis at root of the phenomenon. The only reason I've used the term 'gayness' so broadly is that unless we want to speculate about different causes for different 'levels' or 'types' of homosexuality (I don't), the extent or degree or variety of homosexual behaviour or impulse to same in any specific individual is largely irrelevant for my purposes. Still have grave doubts about its genetic origins though - certainly some of the googling I've done makes an epigenetic basis seem at least plausible.