Nature+Nurture=sexual orientation.

Clearly sexual orientation isn't a binary thing. You have 2 extremes strongly hetero and strongly homo and you have everything in between. Smack in the middle is true bi-sexual. The bell curve is skewed to the hetero side of the bisexual middle so that there are many more people that are moderate to strong heteros vs moderate to strong homo.

Where you have a continuum for a psychological state it means the influence of multiple factors in determining the state of any given individual. Genetics is a part of it, but I'm sure it's not the whole story.

So, the curly question for the liberal minded is, given the multifactoral causation, is homosexuality largely preventable if the major environmental (nurture) factors are influenced towards the hetero outcome? Should research into causation be banned? While people remain ignorant of the true causation in individuals the idea of prevention (or even treatment) cannot come up in public discourse. But as soon as someone does the research and identifies key trigger factors treatment and prevention (or induction) becomes something people will want to do. Imagine: the pink pill causes homosexuality in male foetuses and heterosexuality in female foetuses, the blue pill does the opposite. Should such pills be allowed to exist? What if an existing product, like say caffeine free diet coke causes gayness and normal coke causes straightness when consumed by pregnant women? What if men eating oysters in the days leading up to the sex act causing pregnancy leads to gayness (or at least a significant increase in the chance of homosexuality in the child)?

It's really not the cause that's important, it's what you do with the information once you identify the main causation factors.

Overpopulation

its a habit.

Likely a mixture of several genetic and randomised factors, and quite likely something to do with hormones.

Not that it really matters either way.

Its a Hormone imbalance. ppl are born this way. and no its not a disorder for crying out loud

It's definitely some kind of disorder/defect/error/sickness ... tho i really don't know how it starts.

Some people are just fabulous

Which is not only completely utterly wrong, but stupid.
The Christians are going by what the bible says, but the Bible was written for another time for another civilization, not for today and doesn't apply today.
For example you should not mix clothing of different fabrics, if a child is disobediant they shall be stoned to death.
But the Christians don't take that as literal today, so why should homosexuality be any different?

Also, as for the cause for people becoming Homosexual/Bi-Sexual etc' it is still unknown and any "thoughts" on what causes it, is contradicted by someone else and so on, the way I look at it...
We all bleed the same colour of blood, who cares if 2 guys are going at in the privacy of their own home? They sure as hell are not hurting anyone.

As for marriage, let them have a civil marriage, most would be happy with that over a traditional religious marriage anyway.

By modifying the DNA of fruitflies(just one gene)turning them into albinos,the same gene also turned them into homosexuals.
all albino fruitflies were also gay.

therefore it is mainly a genetic thing.

As the world is not just black or white(eg bi sexuals) and humans are far more complex than fruit flies and genetics could be modified or mutated to intense or weaken homosexual tendencies there will never be one ultimate answer to this question.
Homosexuality also is part of conditioning as the ancient greeks have proven.
They were dominated by a gay Agenda and it was a wanted and common thing for male people having sex with other males(even alexander the great).You almost had no chance to become part of the elite without having sex with other guys.Plato escaped this mess by claiming that love is a spiritual thing(he had sex with women but this trick helped him to protect his anus)
Though male greeks were trained to have sex with other males for centuries and homosexuality was surpressed for 1400 in Islam you will find as many gay people in greece as in muslim countries(though muslims will deny this)
It does not matter if you surpress or worship gays.nothing wikl change.
The percentage of gay males is almost the same ,no matter which country or race you go to,therefore this seems to be part of our genetic code(the same with animals)and as the nature is not reducing this numbers and keep gays at a constant level it seems not be a defect(a defect would have been eliminated by nature or lowered to minimum eg0.0005% but would never remain steadily at5%)

Some people are not afraid of themselves, or the pressures of others. They enjoy life, and embrace the joy of being alive.