I have yet to find many people who do exactly what their parents tell them
"Exactly," no, but that's a bit of a reach isn't it. But your formative years are undeniably moulded by your parents. They tell you about the world, and they form the basis of your opinions and beliefs until you reach an age where (some people at least) have the tools to question that.
As a general rule, Catholic parents raise Catholic children (obviously, as they believe it's the right thing to do), Muslim parents raise Muslim kids, and so on. I'm sure that there are examples of, say, Muslims with Catholic parents, but I'd wager it's exceptionally rare.
I'd love to see some stats on this, but people aren't born religious. So they must get it from their parents, their peers, their family, their community. I'm sure some people find their own way their in adulthood (we've examples of that amongst STW members) but I'd hazard that's atypical.