I'm not sure that telling Billy "Hey, some people live life differently than you do" is exactly ruining his childhood.
No one said it was. Public schools can, and should, teach kids about the different lives people lead, without telling them to accept a behavior that most parents disapprove of.
You're missing the bigger point.
There should be no public schools. What your kids learn should be decided by
you, not some committee of bureaucrats that's trying to be "inclusive" of every possible point of view. If you're very religious, you should be sending your kids to a religious school. If you're in a farming area, you should be able to send your kids to a school where they'll learn about livestock husbandry, farming, mechanical work, etc. If it's your dream that your kid should go to college, you should be able to send your kid to a school that emphasizes a lot more "liberal arts" types of subjects.
I understand the point that "we, as a society, want an equal education for our kids".
But society should not get to determine that! "Society" has no place telling parents what their kids will learn. Sure, it isn't "fair" that your parents might send you to a school that emphasizes agricultural arts and that "limits your capacity for achievement". So what? Who ever claimed life was "fair"
The more we try to make everybody "equal", the worse society's problems will be. We've progressed from making sure that all kids learn the three Rs, to making sure that they're all in school at the proscribed times, to making sure that they're all learning the Politically Correct topic of the week, to making sure that they're "equal" with the stupid, the drug addicted, the violent, etc. In our attempts to treat all kids as "equal", we've dragged them all down to the lowest common denominator in hellish classrooms where the "teachers" care more about staying alive and getting their retirements than trying to teach the unteachable.
Some kids will be, and should be, "left behind", so that all of them don't wind up left behind.