A boy, raised in a gay household of two men will think nothing of two men kissing. That boy will think it is normal for him to kiss that boy in his class. Then he will be beaten within an inch of his life, if not shot in the head.
Er..... You're talking bull.
Many kids grow up seeing their parents kissing. Do they then go around kissing children of the opposite sex?
Some might, but probably more due to their own brain than because they think it's acceptable.
But hey, you see a problem, then what you do is you teach kids what is appropriate, ie, that they should only be kissing people who consent to being kissed.
Your view is "kid might think it's normal so we should ban this". Kind of like Islam making women wear headscarves because men get hard ons looking at pretty women.
Teach kids how the skills they need for the modern world, and you'll have less problems, rather than trying to hide things from kids and forcing people to act against their will in order to "protect" others.