I'm not trying to twist your words, I'm trying to understand your point of view. I confess I'm not sure I do...
From the above two points I get the feeling that you are saying that homosexuality is solely environmental (in-utero and social), whereas heterosexuality is genetic.
Based on this I still come back to a fundamental analytical flaw in your position:
The very exercise of trying to understand what 'causes homosexuality' is in and of itself heterosexist (and thereby subjective) because it takes for axiomatic the assumption that we do understand what causes heterosexuality (which we don't, even if we understand what causes reproductive acts). This assumption implicitly normalizes hetersexuality and marginalizes that which isn't, in that it links the biological imperative of reproduction to the social construct of the male-female pair bond.
I must cry foul here! On the one hand you claim to be citing 'verifiable' and 'empirical' facts yet criticize me for 'nit-picking' when I question the verifiability and empiricism of the conclusions you draw from ancient Greece... and this debate reaches stalemate unless you can actually cite a scientific and 'peer-reviewed' reference that claims to have discovered what causes homosexuality... heck, go ahead and cite one that claims to have discovered what causes heterosexuality for that matter. To my knowledge there are still only theories out there, a gene that determines 'sexuality' has yet to be identified.
The problem here is that you stick to very inadequate terminology, which betrays you in the end:
As we know, the word 'normal' has two meanings in common usage (normal as natural or normal as most commonly occuring), and I can't help but feel you are being coy in playing around with these double entendres because you know very well what an albino means when they say 'their skin in normal', or by extension what a homosexual means when they say their sexuality is normal. To deliberately skew these things is disingenuous.
Also, you indicate that a 'particular' case for bisexuality could be made but isn't this really just to admit that the reality of human sexuality doesn't fit tidily into the accepted, socially constructed view of sexuality as a binary opposite of heterosexual-homosexual?... and really, isn't this just 'Kinsey' stuff that you are referring to??
Agreed. To be fair though, if gay people are touchy about this it is largely because the vast majority of society seeks to normalize heterosexuality (conferring genetics to it) and marginalize that which isn't. At the end of the day the jury may be out on whether homosexuality is genetic or not, but it's still also out when it comes to heterosexuality and it is this hypocrisy that is so frustrating.
Yes and no. Again, if we get rid of the archaic terminology (gay/straight, hetero/homo) we may understand that sexuality lays on a spectrum (Kinsey) where at the polar ends some people may legitimately self-identify as 100% exclusively homo or exclusively hetero, no matter what the circumstances.
Kinsey, like Freud, made many valuable observations, but wasn't sure what he was describing at all. Kinsey said 10% of people were gay, but if he had performed his studies in New Guinean tribes he would have come up with a different percentage in each tribe - meaning that this spectrum he describes is subject to environmental variations and isn't some sort of hard-wired genetic pattern. To say that there will always be solely heterosexual and solely homosexual individuals is not incorrect, but to then assume that the current patterns of sexuality we see in Ontario (for arguments' sake) are therefore a reflection of some unchangeable pattern is wrong on every level. Biology tells us that as much as 95% of the population may comfortably engage in bisexual behaviour under different social standards (which is nothing like what kinsey described).
I suspect your understanding of genetics and perhaps biology in general may not go beyond what you are taught in high school (nothing wrong with that). But you don't actually need to find a gene to determine that something is down to genetics. For decades biologists worked with genes without being able to see any. We know for a fact that there is a huge genetic component to heterosexuality (not necessarily to exclusive heterosexuality, but to heterosexuality regardless of alternative behaviours). 95%+ of men (even many who consider themselves gay) respond with increased sexual drive to a number of stimuli produced by women. 95%+ (being very conservative) of sexually reproducing animals know what to do, how to do it, and to whom in order to reproduce - and they do so for joy and through impulse. There is no need to identify any gene that determines this, for there isn't one gene - there are thousands. The 'jury' is not 'out on that', and I would please encourage you to find a single source that says 'they' are. Exclusive heterosexuality in most of the population, just like exclusive homosexuality in most of the population, can only be explained through post-birth environmental factors. Neither genetics nor in-utero factors could explain this.
Twin studies on the other hand show that about 40% (much less in women) of gay people's
genetically identical brothers are gay. And that the link is strongest between brothers who shared a placenta, and next to non-existant in brothers who did not. In other words, such studies demonstrate that there most likely is a genetic component (though the gene could actually be expressed in the mother and not the offspring - this is MASSIVE), but that there may be nothing in the brothers' genome that makes them shun women and prefer men. Rather, developmental processes while they were inside their mothers may have altered their brain development and affected their sexual behaviour permanently.
There is no hypocrisy in stating that heterosexual sex can be much more easily explained through basic genetic theory than both exclusive heterosexual behaviour and exclusive homosexual behaviour. Exclusive heterosexual behaviour does occur in many species, so there's a bit more material on that (which right wing fundamentalists unfortunately hang on to), but as far as apes and humans specifically are concerned, simple genetics doesn't seem to cut it at all for an explanation either.
I'll refrain from speaking about normality since you are very sensitive to that word for socio-cultural-historical reasons. I don't understand how you think I'm using it and frankly I don't care too much. It should be pretty clear that I'm not passing any subjective ethical judgement on any sexual preference.
You say it's heterosex-centric (or something) to focus on what causes homosexuality, but biologists have been trying to figure out what causes heterosexuality in all animal species for about a hundred years. Once again you are just being defensive (you really need not be with me). That you are not following it doesn't mean it hasn't happened, and as you can imagine it's fairly controversial too as we understand that societal factors play a huge role in stopping most of the population from engaging occasionally in behaviours that'd be considered 'bisexual' by modern standards. The religious right, much like the defensive left (who are ultra happy with the '100% genetic always for everyone' train of thought), aren't very pleased with what serious biology has found so far. They also aren't very pleased with how everything points to humans not being a monogamous species (note how biologists once again focus on explaining monogamy as well as polygamy regardless of a social bias).
To a biologist, listening to some of the "homosexuals are always born gay due to genetic factors and you need not to worry because your kid will be exclusively straight regardless of any environmental factor" feel-good propaganda is very frustrating. It seems to imply that the only reason why homosexuality isn't evil is because it's not contagious, too, which I find ethically questionable!
I'd rather we started out by saying "having monogamous consensual sex with anyone else provided precautions are taken is never wrong regardless of the factors that led to it, but exclusive homosexuality is so rare in nature that in all likeliness your kid will probably go on to date members of the opposite sex regardless of whether he/she can find members of the same sex attractive or not". But in a civil society so immature that we have people claiming 10% of people are exclusively gay and 80% are exclusively straight due to some mythical unsupported genetic factors while the religious right claim whatever is convenient for them instead regardless of anything else... we have a long way to go.