Ask your evolutionist how a "gay" gene can survive even a dozen generations. If you prefer inquire of your intelligent designer what he had in mind if he made homosexuality a built in.
I agree, and it really doesn't have much to do with the theory of evolution. If homosexuality were actually genetic, homosexuality would have ceased to exist thousands of years ago due to the fact that the gene would have disappeared through the elimination of reproduction.
( How they do that is beyond me. The thought of having homosexual sex is so off putting, that I cannot imagine how they could have opposite sex if they are wired for same sex)