Well I'm not sure that everyone needs to know everything, I wouldn't want to have a three year old watch execution videos so she really learns the horror of what goes on in the world.

But for things like sex which are normal and natural and often an integral part of loving relationships and will inevitably impact the person some day since most people have sex at some point in their lives then there's no point hiding it away. That's why I feel it's right that schools do give sex education at an early age so it isn't just left to chance, blindly fumbling through the experience some day.