Ethically, it is questionable, but logically, why shouldn't "the gay gene" be corrected if it is possible to do so? I am going to be hated on to the utmost for this post haha.
If, before I was born, I could choose whether I was straight or gay, I would definitely choose straight. The most important life process, the reason all living things in nature do anything, is to reproduce, and yet gays are not able to do this (comfortably at least). It's not a question of "being normal" or of "fitting in" with everyone else, it's a question of nature.
I do think it is interesting that whatever mutation is in the biological process that brings about homosexuality has not yet been wiped out through the process of evolution. This is what makes me think that it is not necessarily a gene but perhaps something that happens after conception while still in the mother's womb. I firmly do not believe it is created through the nurturing process however.
I have to reiterate for everyone that's going to pounce on me that I AM NOT self-hating or anything. I don't hate other gay people either. I make the best out of it. But given the choice I would choose heterosexuality. And I also agree that a baby should not be aborted just because we can tell it will be homosexual, but I do agree that if it can be "cured" somehow before birth than that is what should be done.