Well, according to the LDS official position, we don't know what causes homosexuality.
here's what i genuinely don't get....
this isn't just aimed at LDS, but others who campaign to get gay marriage illegalized.
regardless of any church's "official position", banning gay people from getting married won't make them any less gay, and won't lessen their desire to get married and keep fighting for the right to do so.
i am a Christian, and i realize that not everyone in the world holds or can hold my Christian views. Jesus Himself says "no one can come to Me unless the Father draw him" (John 6:44).
so why fight against a people, an identity, and a movement? what's the point? it's stupid, and illogical. a Christian will generally state that only the Holy Spirit can convict a person of sin, and lead them to make a u-turn and repent.
spending lots and lots of money to prevent people from doing what they want to do and feel they have the right to do won't accomplish that. it's forcing a personal belief system on non-believers who are Biblically speaking unable to understand the Christian position unless convicted by God. in the mean time, lots of money, energy, and vocal volume is spent looking vindictive, and making life miserable for a huge chunk of the population who genuinely doesn't understand the basis or validity of your convictions.
so why all the effort and money wasted? i don't support gay marriage. i believe that God has blessed and sanctioned marriage to be between a man and a woman. but my gay neighbor isn't going to get that, or share my belief. i believe he is living in sin, he thinks he's fine. and someday, he might want to get married to his boyfriend. should i try to stop his wedding, or slash his tires so he can't make it to the court house? that would be insane, and really mean and illogical.