Like lying.
Taught ( with much pressure, emotion, upset, and frightening glares) that lying is wrong, and then it turns out , not only that almost everybody does it, but that in 50% of cases this is considered a good thing, called being polite, etc.
It also seems to depend on who's doing it, etc
I'm AS mother of AS boy. I also put great pressure on him about lying at one time, but have stopped since understanding this. And talked about it too. Now I don't treat lying itself as such a crime, especially if was out of fear to cover up an accident. It still bugs me though, because it is a battle of wills.
But about society's hidden laws i guess i "teach" him just by muttering wrathfully about them from time to time!
