I disagree completely with your first statement.
There is no logical consequence of that statement that would lead to sexual orientation being a choice. For example, the fact that your native language is English (or something else) is certainly not genetic, but it is also not a choice.
I suggest that you read what I have written more carefully - particularly in post 33. I did not say that the logical consequence of the original assertion that homosexuality has no genetic basis is that sexual orientation is a choice. I said that the logical consequence was that sexual orientation is all down to environment. I don't known the origins of sexual orientation - they haven't been determined, but dunno260's 'personal view' pretty much accords with mine - that is, a combination of genetics and environment, with genetics being a necessary, but not sufficient, factor. Recognise, however, that this is a personal view, not an empirical-evidence based view, as the evidence is not yet available. Despite all if this, IF it were found that it is all down to environment (about which I would be very surprised) THEN a strong argument can be made that sexual orientation is changeable - and it could be argued that this is a form of 'choice'. I wouldn't find such an argument persuasive, but I do recognise that such arguments can be built from findings that homosexuality has no genetic basis.
If you disagree that the logical consequence of a finding that genetics plays no role is that sexual orientation must be environmentally determined, then please address the comments I made in post 33.
Also, I think it's rather anti-intellectual to "be careful" of certain ideas because they might lead to unfavorable consequences.
You have misinterpreted my intent - I meant be careful when making sweeping assertions which are unsupported by evidence and which have significant logical consequences. I assure you that no one who knows me would ever describe me as 'anti-intellectual'.
In other words, I think it would be wrong to suppress scientific research on genetic/social-constructive/mixed origins of homosexuality because it might make people think of gays differently, or even if it makes people question gay rights. The genetic route is rather convenient because then no one is to "blame," and there's a certain clear-cut nature to having a yes-or-no genetic test result. That doesn't mean that it should be the correct explanation. Maybe it's because I come from a science background, but it bothers me when people align themselves with a scientific proposition, not because of empirical data and scientific rationalization, but because of politics.
I would never, ever, ever, in a million years, assert that scientific research should be suppressed, directed, guided, manipulated, or re-interpreted on political grounds. I am a strong believer in academic and scientific freedom and integrity, the importance of empirically-based research, and ethical research. Given our difference in ages, I am almost certain that my science and research background is more substantial than yours (this is not meant as a put-down, it's just a fact). I agree with you that the relationship between science and politics is a difficult one - but I, for one, will side with the empirically-determined over the passionately-asserted, and would agree that politics (and, for that matter, religion) should be kept out of science to the greatest extent possible.
Regarding the origins of homosexuality (apologies to OP)
Identical twins are not the same sexual orientation 100% of the time, so it is not determined genetically. In fact, most studies (Google search for sources) put the percentage close to 50%, which would actually suggest that identical genetics neither heavily favors nor disfavors identical sexual orientations. If you consider environmental effects to be the only other source of influence, then it follows that it must be significant.
Firstly, I didn't say that anything was determined genetically (or environmentally, for that matter). Secondly, my interpretation of a 50% 'same' rate is that it stongly suggests genetics is important - I'd be interested in how you came to suggest otherwise. Thirdly, can you suggest
any potential source of influence beyonds genetics and environment, taking 'environment' in the broad sense?
For environmental effects, a good way to test is to look across cultures. Are there cultures where the homosexual population percentage is higher than, say, the United States? If there is a difference in certain cultures, then perhaps culture has a significant influence. Certainly these studies have been done, but you get the idea.
Yes, they have, but as in any study that claims to provide information about the proportion of a population that is homosexual, the methodological issues make interpretation difficult. Even so, cultural factors are just a sub-set of environmental factors.
