I believe full blown homosexuality is something that is in the DNA. It's not a choice. You can't just choose to think your way into falling in love with another man. But I also don't think it's nature's intent. I think it's like anything else that our DNA goofs up on like bi-polar disorder, autism or schizophrenia etc. Why? It's simple. What are we taught with regards to evolution and nature? That the goal is to survive. The survival of the species is all nature cares about. That is it's only goal... to keep going. So if that's the goal of nature, then two men or two women fucking eachother is akin to suicide. It doesn't make any logical sense at all... unless you believe that being gay is natural selection at work.
I support gay people 100% and believe they should be treated with total equality. But that doesn't mean I think it's "normal"... in the same way I don't think manic depression is normal, even if it's a natural occurance.
You're right in saying it's not 'normal' in terms of evolution, but to have a physical reaction (OP said feels like vomiting) at the thought of two men having sex isn't normal or rational even if you justify it evolution or whatever. Look to what the other person said about conditioning
How do you know is not normal in terms of evolution when hundreds of species including insects show homosexual behaviours?
