A common response to hearing that sex between two men or sexual activity between two women is immoral is either "I was born gay" or "Some people are born gay." The first problem with this, of course, is that babies don't have any sexuality or sexual desire. No newborn babies are sexually attracted to the same sex as them, because no babies are sexually attracted to anybody or anything.
Ok, maybe they mean "I have immutable sexual desires for members of my same sex" or "Some people have immutable sexual desires for members of their same sex."