> Children have no concept of violence or empathy or right or wrong

This is not correct. I remember having a sense of shame when I was 4 when I tried to hurt another kid. Kids will also hide the things they do wrong, because they know it is wrong.

> because they know it is wrong

Or they know they'll be told it was wrong. Children start knowing nothing then they slowly absorb what they're told again and again, and what they see around them until they feel it. They go from knowing nothing, to knowing what the adults told them, to internalizing that and feeling it rather than just knowing it (maybe these 2 concepts fully overlap in other people's minds).

But until they do get all of that, they'll spend a lot of time plucking wings off of insects, burning ants with a magnifying glass, pulling the cat by the tail, or throwing rocks at dogs and frogs.

> ... because they know it is wrong

No. They hide the things they do wrong because they learnt there are consequences and they dont want to get caught.