He clarified his post here:

So no,it's not evolution,it's just part of a larger picture of self-destruction of Western society which we can see in abismal birth rates,destruction of traditional family and secularisation (disappearence of religion).

Accepting homosexuality will naturally lead to lower birth rates, while rejecting homosexuality will lead to higher birth rates. If we rejected homosexuality, then most homosexuals would realize they were wrong, change their sexual orientation at will, and procreate with the opposite sex, increasing the birth rate. But because we can't do this, we cause a net loss in birth rate.

And yes, a low birth rate is very bad. The Western society's current birth rate is simply too low. We need to increase it because if we don't make new babies at a faster pace, the Western society will be destroyed. We need to create more people and at a faster rate.

And homosexuality obviously opposes certain religions.

hell no, evolution is meant to strengthen the race no make it weaker, by that I mean our main goal as a human being is to reproduce and having attraction for the same gender reduce the likelihood of producing offsprings

Look.. I don't think anybody knows what they were born in terms of any leaning in life. I really can't see the connection. Sure if they was some sort of blood test that could be done to see that I have a leaning towards curvy brunettes and you have leanings towards whatever type of person you are interested in I would agree.  I'm certainly not suggesting that every gay person was molested.  I just don't think that mine or your sexual orientation is something that science could back up as being something you're born with.  I think I could have the exact chemical makeup I have and in another life I could be gay. What I'm curious about is why it matters to you? I'm 100% a backer of gay rights and put people in their place all the time for bashing homosexuals but I'm also a big fan of science.  Why does this scientific opinion I have bother you?

Saying we were molested in our childhood =/= not scientific.

I don't buy that you're not homophobic, not what that ridiculous view on molestation. It doesn't bother me that you think it isn't nature, plenty of people do and don't.

We already have lots of orphans. Don't you think letting them be adopted and raised by two parents (no matter their sexuality) will strenghten them as individuals, and thereby strenghten society? In fact, if they enjoy their upbringing it should encourage them to have their own children eventually.

Not to mention that there are surrogate moms and insemination possibilities for when homosexual couples wish to have their own kids. Well, in truly developed countries, that is.

This pretty much sums up my point of view. From an evolutionary standpoint, people with lack of sexual interest or sexual repulsion of any form would be at a disadvantage to those who don't. Ultimately it makes most sense for sexual orientation to be primarily environmental.

This doesn't have anything to do with evolution

His point has some merits though. As we all know, when a baby boy is first born, he is slapped on his ass by the doctor to check his reaction. Sometimes, the doctor may be a little frisky (molestation) and the baby may like it, which leads to them being gay. There needs to be a study on homosexuality and intensity of post-birth ass-slap.

Let me preface all this by saying I support gay people and their rights.  That being said, in my opinion, there is no such thing as gay tendencies.  You're either gay or you're not.  I have not once thought, "I wonder what all the fuss is about, I want to have anal sex with a man".

That being said, I think many gay people go on to marry straight and produce offspring.  As being gay become more and more acceptable, less gay people will (in theory) marry straight, thinning out the "gay gene".  That's how evolution works.  Of course, NONE of the above accounts how the gay gene came about in the first place.  If it is a mutation due to some outside factor, there is a potential that two straight people that come from a lineage of straight people still have a gay child.

Just learn to tolerate everyone and move along.