Nature is a more powerful influence than TV and movies could ever be, on sexual experimentation. Take a look at the Mormons or those buggy-riding guys/gals (Can't remember the name right now). They don't have the kind of exposure to television and movie sex, magazine advertising etc...that America JR does...but they're still going to be driven, by their own biology, into experimenting.
Mom and Dad can scream "Just don't do it" to their hearts content, but once the blood starts boiling...those screams with just vanish. At that point, you can either have a pair of kids with some idea about what teh consequences of sex can be (including pregnancy, STDs, etc...) or you can have a pair of kids who heard from someone that "If you stand up after sex, you can't get pregnant" or "You can't get pregnant the first time" or any other number of inanities.
It's a matter of hormones vs. teaching/religion/parents ... and you know what? With one arm tied behind it's back, hormones will win out every time!
s'nuff?