Kinda yes, mostly no. 8-ish is the age where kids start developing some sense of morality past "this is bad because I get punished when I do it". I don't know where JS Jr. got this particular piece of doctrine from, but much like everything else, I'm certain he stole it.

Neuroscience tells us that somewhere in our early 20s is when we really finish our moral development. Which, again, is why there's a push to get kids out on missions the second they're 18 (used to be 19); that reinforces all the garbage they've been taught up to that point.