I posted it earlier, but I'm happy to do so again.OK, show me any evidence of "holy parents" who do "teach their kids about this", and back it up with scripture which orders sex education. So far there's nothing supports your version of "holy" regarding this matter, but evidence against it.
"Train up a child in the way he should go: and when he is old, he will not depart from it." (Pro 22:6)