“If our parents don’t teach us manners and behavior, then we stay that way the rest of our lives.”
There are other ways to learn.
Other kids or their parents can deliver the message.
Good schools that maintain discipline can do the trick.
Boot camp is good.
Prison sometimes helps.
The problem is when there are no guard-rails anywhere to be found.
Certainly worked for me.
Sometimes a smash in the face works as well (to teach manners) but females will likely never have that happen to them as men with manners will never hit them.
Biggest problem in our society is impulse control. And certain segments of our society is "most vulnerable" if you catch my drift.