My personal opinion is that censorship doesn't work. What can work is timeslot shifting, which means that you air all adult stuff after 11PM.
Why doesn't it work? Because people will still get what they want, one way or another. Legally, you cannot drink before you are 25, marry before you are 18/21 (debatable), or have "consensual relations" before you are 16. However, all of this happens on a daily basis around the world. You cannot stop free will, because once someone is determined to do something, he or she will do it regardless of what you have to say about it.
In fact, I was 8 years old when I started playing gory shooter games. I was 9 when I first encountered "pr0n" on the internet (accidentally). Incidentally, I'm not violent, don't play games a lot, am highly social, have no incidents of drinking or smoking, no girlfriend(s), nothing (I don't even watch "dirty" movies. I swear to God about this). I'm "squeaky clean".
Like I said, these things only matter if you have the inclination from the start. Censorship simply doesn't work and these things have very little role in shaping anyone's lives or personalities.