I'm fortunate enough that my folks remain in pretty good health, all things considered, so it's odd to speak of them in the past tense, even for the sake of this thread. In our house, mom was the everyday disciplinarian, meting out punishment as required, ranging from yelling and screaming (she can hit some notes), to the wooden spoon or paddle (a practice she disavows today, and encourages her children never to take up). You're never too old to reconsider, I guess.
My dad was always a quiet one; really almost never yelled, and never once hit me. He tried once (how mad he must have been!), but I danced out of the way and took off for a few hours. But here was the thing: because my mom had such a quick temper, I wasn't really afraid of her punishment. But my dad - who remains about the gentlest man I know - was the one who could scare me, and if he said do it, I did it, because of the unknown. I figured he had a limit, but I just never really got there ... and never wanted to. I guess it was respect, but backed by a little bit of fear.
(Just as an aside, my mom wasn't afraid to get after it. She still tried beating my ass (I'm really just talking about an angry spanking here) until I was 13, when I was already north of six-foot and 200 lbs. By then, I could pretty much fend it off and restrain her, so I think that's when she finally gave it up...)