OK - raise your hands, all you people who've studied Zoroastrianism in order to not become a Zoroastrian! Personal beliefs are what we know about and accept. What we don't know about doesn't affect us except in our interaction with others. A culture is made up of what folks have in common. Those things that are passed on through generations - stories, songs, methods for doing things, etc - provide a frame of reference, a language.

I think children's culture changes all the time, and can be quite drastic. My own parents probably lamented the fact that I talked like the dog in the Jetsons instead of Betty Boop, (mis)remembered lines from Star Trek ("The evil must be destroyed. YOU are the evil!!"), but Flash Gordon was a stranger.

Kids don't personally encounter the same things previous generations did. What happens is someone who does remember tells the kids about it, as Penny will be doing with the sock-washing shepherds. Perhaps the greater part of our surprise comes from finding out we're the ones to be doing the passing-on because someone else hasn't already done so.