I certainly don;t want to discriminate against anyone. I would NEVER call anyone names or use violence of any kind. My arguments are strictly behavior oriented. There is no argument that people are born heterosexual. Our sexual parts are designed for that. There is no proof anyone is born gay.
What about the poor souls that are born hermaphroditic? Or the children who have been injured during birth and are out of necessity given a sex change? (I'm thinking back to a couple of baby boys who were burned badly and had to be changed into girls, I don't recall any going the other way.)
Also, sex in the human world is not solely, or even mostly about reproduction. If it were, then we would not have so many infertile couples. I think most here know that I am a fairly outspoken Christian, and I do not feel that God would create sex for reproduction and then torture women by not letting them reproduce!
Eve was created for Adam as a partner, and sexual relations bring partners closer together. It is a bonding like no other. I believe the *perfect* way would be for everyone to come to their marriage bed as a virgin - in a heterosexual relationship. But this is not a perfect world.
There are times when men and women do not find the love and compassion (or sometimes some elusive something that cannot be defined) from a member of the opposite sex. Sometimes there are psychological reasons for this, sometimes there are events that have happened in the past, but sometimes I believe that, yes, the body's physical makeup can play a role. Just because a person is born with a certain set of sexual organs, does not mean that their brain and endocrine system is putting out the correct amount of hormones.
But it is not our place to judge or even question who loves whom on this earth. As a Christian it is my responsibility to introduce people to my Savior, and then they can decide about what changes, if any, need to be made in their lives. I am only responsible for the changes that need to be made in my own - and possibly the ones in my children's, for as long as they are still innocent, and I am still teaching them.