That's a good question, I'd say at least until the age of 12, it's a bit of a random number, but I think that at that age children are a little more prepared to face the prevailing evil.

those are pretty bad, agreed!

to what extent should the information about the evil world be shielded from the children's mind and up to what age? 

SHA256man

I believe that many of the worst conspiracies have to do with children, our society starts with children, since it depends on them, and let's look at the world we are creating for them and what they do with them as well.