Like most kids, they still got into trouble and had major screw ups in their young lives. However I've never seen anyone who respected their parents more in my life. There were no beatings, no yelling, no destroying or selling of their property as punishment. And wouldn't you know it, when they got in trouble for something they did wrong - they didn't resent their parents for it. They were always expressive that their mistake (or the general view of society that what they did is a mistake) was the problem.
It's hardly empirical evidence but it certainly convinced me.