If homosexuality is not 100% choice, then why on earth would it matter whether it was genetic, or some other biological factor? That seems like hair-splitting, since it doesn't seem to matter to the overall debate.
Does it make you anti-science to posit that the biological factors involved in sexual orientation derive from genetics? I've not read up on it, but why on earth would you need a "gay gene" at all? I would think sexual orientation would be influenced by one's balance of hormones, which logically seem to derive from heredity.