How do I know God is real? The same way you know love is real, I have experienced Him and His presence. How do I know the Bible is accurate, which I think is your point, because archeology has shown the historical accuracy of the accounts in the Bible.
How do you know dinosaurs are 83 million years old? The only correct answer is through faith in palentology, since palentologists cannot prove an ancient age for the earth. You put your faith in some supposed scientific proof that homosexuality is genetic and I put my faith in God. You cannot experience science as I have experienced the presence of God and how He has changed my life. So I know the Bible is true by faith just as you know by faith that dinosaurs walked the earth 83 million years ago. Now, before you jump up with scientific "proof" for you position concerning dinosaurs I suggest you read the Science Forum.
Do gays exist? Yes, they do but so do ex-gays and just as you demand accceptance for your life I have the same right that you accept the fact that some people can and have changed their sexual orientation.