Excerpt from a Star Tribune article:
The strongest predictor of whether a child thinks its OK to hit kids, and whether hell grow up to do so, is how often hes been disciplined that way. Light spanking isnt as bad as wielding a tree branch. But its part of the continuum. Researchers call this the hidden curriculum: Corporal punishment teaches itself.
Peterson thought he was teaching the opposite. According to reports, he was punishing his son for pushing and scratching another child. He says he explained this to the boy. Anytime I spank my kids, I talk to them before, let them know what they did, and of course after, he told investigators.
But when you hit a child for hitting another child, the hitting does all the talking. Thats the upshot of a recent study of more than 100 children and their parents. Every parent who approved of spanking a child for hitting a sibling passed this belief on to their kids. And 79 percent of kids who came from homes with lots of spanking said theyd hit a sibling for trying to watch a different TV show almost the same scenario that led to Petersons beating of his son. According to the researchers, Not one child from a no-spanking home chose to resolve these conflicts by hitting. The kids absorbed the model, not the lecture.
http://www.startribune.com/opinion/commentaries/275304271.html