Homosexuality - Fruit flies and choice
J. David Velleman at Left2Right has a good post on recent scientific findings on the topic of sexuality. He makes some good points about choice and morality.
The discovery that the purely instinctual behavior of fruit flies can be manipulated via a single gene cannot lead to the conclusion that the corresponding behavior in humans is not a matter of choice.and
Scientific studies have indeed indicated that variation in sexual orientation among humans has some heritable component.1 But these studies also exclude the hypothesis that sexual orientation is fully determined by genetics. To begin with, virtually all research on sexual orientation relies on something like the "Kinsey scale", which measures orientation on a seven-point scale (0 to 6). The lay conception of homosexuality as an all-or-nothing trait has no basis in scientific observation. And the best-designed studies of identical twins have found that in over two-thirds of the pairs that include a homosexual twin (scoring 1 or higher on the Kinsey scale), the other twin is not homosexual.2 This finding decisively rules out the possibility that sexual orientation is genetically determined, though further statistical analysis shows that it is indeed significantly influenced by genetic inheritance.
However, one thing I do take issue with is the following statement....
Dr. Weiss is hoping for a scientific discovery that will "take the discussion about sexual preferences out of the realm of morality." Now, I too believe that sexual preference should not be moralized. In my view, the moral issues in sex have to do with consent, love, mutual respect, honesty, faithfulness, and responsibility for consequences, not with the anatomy of the partners.
The problem here is that when you talk of love and mutual respect you cannot divorce this from the harmful acts of homosexual sex. Study after study reveals this to be the case. Yet how is it loving or a sign of respect to intentionally harm the one you supposedly love and respect? Clearly, you cannot escape 'moralising' on sexual preferences by appealing to such other factors as they are clearly linked.