A. Evolution, Science, Logic is flawed, and homosexuality is in perfect natural order.
Or
B. They are all still valid and homosexuality is not a natural thing and is therefore is one of the 2 choices presented above.
I don't think you understand at least three of those theories, nor fairly basic statistics. Maybe homosexuality will die out in thousands of years through natural selection, or maybe it's something that is based on something so fundamental that it can't. Who cares? We're talking about today, not 10 000 years. Maybe we'll all have gills by then. It's not really that relevant.
Anyway, I'm going to go with the "mixture" vote: probably both genetic and due to the environment. Most things seem to be.