I personally, am not gay, however, there are completely logical reasons for one to be gay. I do believe it is a choice.
Right now, our home planets life support for our race and others is beginning to run slim, for us to survive for a very long time, we must stop having children at astounding rates. But why, due to being considerate and having children no children, should one sacrifice the pleasures of sexual desires?
Imagine if half of all of the Chinese in China turned gay, I bet their over population problem would be solved pretty quickly. The homosexuals would be happy, the people who specifically want to have kids will be happy (because they can have more). People just need to be open with each other...
By one being gay, she or he is (often times) revoking the ability to bear a child of his blood, and may even adopt to take care of a child who would otherwise have no caretaker. With adoption orphans are becoming fewer. What's so bad about that? Are orphans being rescued and children no longer starving not good enough reasons for people to open their minds a little more?
Though sex may actually be a benefit to the health of humans, sex with multiple persons has proven itself to not be beneficial in the long run. Without monogamy, those who have sex with multiple persons, may kill many people during and after their own lifetimes, unless extremely careful. Practice safe sex, it might be a good idea.
Of the infinite options, it seems that at this point in our humanity (2007) it may be equally logical from a humanitarian and an equalitarian (for all animals/Earth) point of view to be either homo, bi, hetero, or asexual. It can be morally righteous in its own sense.
I just want to make it clear that I do not think homosexuals shouldn't have children, but think that because often times, they do not bring new children into an over populated world, they could be righteous in their own sense. I think we need both, a balance of them both.