Normal does not have anything to do with anything except that always, throughout the history of humankind, a certain percentage of the population has been homosexual. They just are. Same with left handers. No amount of disapproval from others is going to change those facts. So, it's normal. Just like it's normal for some people to be born gingers, even though they aren't the majority. it's still totally normal.
I am left-handed. Thank god the ignoramuses who tried to force lefties to write with their right hands were long gone by the time I came into this world. Also, thank god most of the people who make moral judgments against homosexuality and ginger-ness are also long gone.
It won't ever lead to the end of the world because everyone will never be gay.
Also, the end of humanity will not be the end of the world. Just sayin. LOL