Filtering is not and never will be a foolproof solution, because those who wish to beat the system will do so with ease. Yes even kids!

The far better solution is that parents/guardians take it upon themselves to "child proof" their environment, be it real world or virtual, as much as possible.

Educating children about sexual related matters should always be the duty of parents', to make sure one's kids get a healthy and informative idea of their sexuality as opposed to the warped,malignant and destructive notions they can gather from corrupt sources. Being shy and awkward will not help in this matter!Teach them not only about the birds and the bees, but the predators and demons too.

And of course you need to constantly monitor your kid's actions and activities. It's becoming far too easy for some folks to make the computer and television their nannies, leaving kids to entertain themselves unattended for hours on end even. This is by far a disaster waiting to happen.

Finally do not overestimate or underestimate kids..ever! And don't judge them by your own character. I know people who have given far too much freedom to their kids to do what they wish with the notion that "I didn't go astray so they won't" or "I am God fearing so they will be ok" BAD IDEA!