Is it wrong to shelter kids for too long?

My parents are pretty much nazis on everything sex related, if a tv show says any sexual joke I can't watch it, if a game has anything close to nudity I can't play it. I do think its good for little kids to be sheltered from this stuff, but I'm 15. So, for the past few years I've been watching all these movies while their out of the house and I'm wondering if my parents are right and I shouldn't be watching South Park or Robot Chicken etc.