Do you think that homosexuality can have environmental causes?

Of course! I think EVERYTHING in life is a mixture of nature and nurture. Whether it's our sexual orientation or even our personality, we're all products of our surroundings and genetics. To say sexual orientation is solely due to genetics is ignorant.

I'm bi-sexual, and i don't think this tanong is rude or offensive in any way at all. MasterOfFear asked a simple tanong as he/she is genuinely interested i think.
Like someone above sinabi (i forget who i apologize) the whole pagtatalo of nurture vs nature has been going on for years and can't be dealt with just two options available.
I agree that someone's past life experiences can push them to a decision about their sexuality, but i also believe it is the individual person that bears the whole responsibility of who/what they are or wish to be.
Being gay, homosexual, heterosexual, bi-sexual or anything else for that matter is no shame and shouldn't be hidden. I suppose it all depends on personal experiences and feelings towards others and yourself.
For me, i went through various stages in my early teens before i came to the conclusion that i was bi-sexual. At first i thought i was gay, as the only people i had been with and felt true pag-ibig for were women, but when i left school i dappled around with both men and women and realised though i loved the connection with women, nothing set men apart (for me that is). So i like both although i'm settled now so my dappling has come to an end i believe LOL.
There's too many sub-clauses and loop holes to choose between two very different reasoning as to why people become gay/straight/bi. That's my opinion anyway, but i do agree it could be a little both (nature/nurture) that holds the decision.

Or they could just like people of the same sex...? God damn, you act like they're freaks that have to have some cause for why they're different. Nothing "causes" it except an attraction to the same sex.

im offended because im bi and this tanong is straight up rude

The whole nature vs nurture pagtatalo is in fact an ongoing one. I think it's a combination of both. It could very well be possible that upbringing or rather experience with not just parents but everyone in general can be a sort of facilitator if you will, while (non)sexuality is inherent in all of us. In my opinion, genetics predisposes us to a particular sexuality, while nature or the environment simply furthers the expression or the suppression of sinabi sexuality, at least to an extent. But the whole issue is much too complex to point out a singular factor as being the cause.

While serial killers' backgrounds and histories are interesting, maybe you should have cited examples that aren't quite so extreme. Maybe examples of the layperson because you're addressing people in general here, not serial killers. Therefore, people might find it offensive that you're comparing potential causes of sexuality of serial killers to their own. Or they just won't be able to relate to the tanong as much.

I don't think so, I was raised sa pamamagitan ng Christian parents, who tried telling me that homosexuality is a wrong lifestyle. But I'm bisexual. I feel that it has madami to do with nature than anything. Maybe it's different for others.

I'm Bi and I agree, this tanong is kind of rude / offensive.

I think it is just genetics, but the things around us could bring it out more. One reason why I say it's genetics is because I watched a film a few days ago, called "The Making of Me," with actor/singer John Barrowman. He tried to discover why he is homosexual. And in the film, it shows two male twins who live the same lifestyle and are exposed to the same things, except one is far madami feminine, playing with Barbie mga manika and such.
If anyone is interested in watching this, link.

Also, I am a lesbian and I don't find this offensive in the slightest. I myself wonder about this kind of stuff too. :)