The importance of this cannot be overstated. I've long advocated for raising kids without the use of corporal punishment, from a place of understanding and explanation. Y'know, the way you'd want someone to explain something to you, but while still being firm in my lines and boundaries, as well as my expectations for behavior.

Keeping an even tone, even when you're frustrated as an adult with your child's behavior, is paramount. You're the adult, right? It's your responsibility to act like the adult. Otherwise, like you said, you're just passing it on to the next generation, and they'll learn to do the same thing.