Why are people gay?

I have wondered why some people are gay. I can only come to the conclusion that people are either born gay, or that they are gay as a result of very early influences in their lives. As you pointed out, it seems to be very difficult in the present-day world to be gay; it therefore seems unlikely to me that many people would choose to be gay if they had the option to be something else. In the days when it was treated as a psychological abnormality, it didn't seem to stop people from being gay - it seemed only to serve to make them ashamed of what they were, so it seems to me, once again, that if they could have changed, they would; therefore, it must not be a choice.