The end of homosexuality?
I've always leaned toward the hormonal-imbalance-in-the-womb theory myself. Homosexuality can't be a simple gene-linked trait; any trait which has such a negative effect on an organism's chances of reproduction would be weeded out of the gene pool very quickly by natural selection if it were genetic. Nor can it be a "choice". I know for a definite fact that I could not cause myself to become homosexual by an act of will, and any other heterosexual person would say the same. So I can't believe that those who are homosexual became homosexual in that fashion. Moreover, the existence of homosexuality has been well documented in many species other than humans.
The point is, soon we won't need to argue and speculate about this question any more. We'll know.
To Sullivan, who is himself homosexual, this has some alarming implications. If the biological basis for a condition is thoroughly understood, it is theoretically possible that it could be changed (some would say "cured") -- that is, tests could be done to find out whether a fetus in the womb is going to be homosexual, and if so, hormone therapy could be applied to change its orientation to heterosexual. Or a homosexual fetus might simply be aborted. The implications of such developments would be troubling from a variety of perspectives.
In the years to come there will be a huge, bitter, complicated ethical debate about this subject, and that debate will be utterly irrelevant and pointless. Regardless of what arguments anyone makes, the therapeutic eradication of homosexuality is inevitable. Here's why.
As long as abortion remains widely available -- and it will, no matter what the Christian Right thinks -- it will be impossible to selectively prevent just those abortions which are sought for certain motives as opposed to others. We can already see proof of this in China, India, and South Korea, where a strong cultural preference for sons over daughters has led to selective abortion of female fetuses on a massive scale. At least in China, abortion for the purpose of gender selection is illegal, but that makes no difference. The technology is available, so people use it, as can be seen by the considerable imbalance of the genders already observable in the three countries. (Needless to say, a large excess of males in a society has terrible implications for future social stability, but governments are helpless to prevent the phenomenon, and the masses apparently either are too short-sighted to anticipate the future problems their behavior is creating, or simply don't care.)
In the case of homosexuality, the matter is even more clear-cut. Virtually all parents would prefer that their children not grow up to be homosexual. Even those with very socially-liberal views, who are genuinely free from any prejudice against homosexuals, still know that being homosexual greatly increases the challenges and problems a person will encounter in life, and diminishes his chances of happiness. Furthermore, most people have, to some degree, a certain feeling of disgust toward homosexuality -- even people in cultures where homosexuality has never been considered "sinful". (I believe that this feeling of disgust is rooted in the genes, but that's a subject too complex to get into here.)
Once testing for incipient homosexuality in the womb becomes widely available (whether legal or not), we will rapidly reach a point where practically the only children destined to become homosexual who are still born will be those whose parents have personal beliefs that rule out abortion. (Most such people are highly religious and therefore likely to be prejudiced against homosexuals, which will create another set of problems.) If it later becomes possible to "heterosexualize" the developing fetus using hormone therapy instead of aborting it, the number of new births of children who will grow up to be homosexual will fall to practically zero. After that, only life extension technology (enabling existing adults to live indefinitely) will prevent homsexuality from vanishing entirely. And even then, eventually a day will probably come when it is possible to change the established sexual orientation of adults (via biotechnology, not the preposterous "ex-gay ministries" which currently disfigure the discussion of this subject). Despite the fact that in the last few decades homosexuality has bizarrely evolved into a sort of quasi-ethnic identity, with "gay pride" and suchlike, I suspect that a fair number would opt for such therapy if it were available and proven effective. Being homosexual does add considerably to the problems and frustrations of life, after all.
The prospect of such an outcome would doubtless make many people unhappy. Yet it is consistent with the way humans actually tend to behave when offered new technologies to exploit.
Update: More thoughts about this issue on Sullivan's site here. One of his readers makes a very interesting point: in a present-day case somewhat parallel to this scenario about the future of homosexuality, Down's syndrome is already detectable at the fetal stage, and about 90% of fetuses which carry this defect are aborted, with the result that the syndrome is disappearing from the population. But the proportion of the US population who claim to be morally opposed to abortion, and even assert that it should be forbidden by law, is certainly much greater than 10%. So a substantial fraction of these Down's syndrome abortions are taking place among people whose stated position is that abortion should not be permitted at all. That is to say, they are utter hypocrites.