Health: People don’t discover it mid-life. It (in many cases) grows in time, just like normal sexual attraction does for normal people. Most people who come out, even if they didn’t realize it at an earlier age, realized that there was something not normal in there heterosexual relationship.
What does happen nowadays, which R”L is caused by the good publicity that homosexuality gets, is people who are attracted to both genders who will choose to let their homosexual attraction become dominant (whether subconsciously or consciously).