I've never seen gay men kissing in front of me and I can't remember not understanding the concept of homosexuality. It's literally like explaining what an apple is. I guess OP and everyone else by "explain" actually mean justify which isn't necessary, if your kids they're gay despite of your it's unnatural lectures. and if they're straight it's irrelevant to them.
The obsession was homosexuality and almost exclusively male type is odd. No one here talks about lesbianism is a perversion, abomination, mental illness etc.