Adultery is natural in the animal kingdom, incest in natural in the animal kingdom. Do you propose we ignore what God has to day about both of these behaviors?
Some men and women develop homosexual desires due to childhood trauma and can through proper counceling overcome this behavior. Those who cannot can control their desires in obedience to God's revealed will.
I would be careful who you call a lunatic. What Paul labels "unnatural" is unnatural for men in God's perfectly designed universe. What animals do as the result of situations and any possible genetic abnormalities due to inbreeding and other factors is immaterial to human beings.
Now since you seem to be an evolutionist before you go any further with that thought it involves science. All science discussions (other than genetic research pertaining directly to homosexuality) are to be held in the Science, Creation, and Evolution Forum.