I can't speak for nowadays but I sure got most of mine from my Mother ! That's where kids should get most of it. I believe it's the parents responsibility to do so. They make get some elsewhere but it's really up to the parents to teach their kids these things.
It should be and it should start very young. I hate when a toddler grabs a toy from a another child and the parent brushes off as "He is just a baby and doesn't know better." Of course they don't know better, this is your opportunity to teach them better.
Yeah, sure it is. It's their moral responsibility. It doesn't always happen for many reasons. Parents aren't the only teachers.