And the adults need to make sure that when the kids make poor choices, they are not likely to be deadly. I have a lot of friends who are raised by their grandmothers and aunts and uncles, and just because they aren't raised by their biological parents, doesn't mean that they have no values. Any sound adult figure in a child's life can really instill good values. Just because the figure might not be their parents doesn't mean anything. I will admit that a lot of children who see physical abuse turn out to be violent people, not necessarily because of that reason, but they use that as an excuse.
Some people do turn out to be normal people, they just keep it hidden inside of themselves.
It all depends on the type of person they are. Any child who witnesses domestic violence has emotional scars, and if those remain unhealed, they can lead to violence as well as to other sorts of problems. Second, children model their behavior, consciously or not, on what they see in their environment, and this is particularly true of what they see in their families. And we all know that. It's the way humans are, even if we are amazed by that, for example, we become shocked at how people act like their parents.