Of course, I'm generally an atheist (and sometimes agnostic on really pretty days, or when I find a forgotten 10 bucks in my wallet), so I tend to have friends with the same general mindset.

But my parents and grandparents all grew up going to Mass every week, no fish on Fridays (or is it just Fridays during Lent? I feel like it's the latter, but some practice the former...), all that stuff. Then as our parents had us, they made token attempts (We went to Mass... usually, I had my First Communion, was Confirmed, etc), but as we got older, a lot of the people I know just sort of drifted away, until suddenly one day waking up, looking around and going "Huh. This is all kind of silly. Yeah, I'm not Christian any more."

I'd say the only friends of mine that have stayed a bit more to their parents stance on religion would be most of my Jewish friends. Dunno if it's because the culture and religion are so intertwined there, or if it's just that they have really overbearing mothers, but there it is.