Family Roles

I was encouraging Katherine to climb the stairs.

Me: Come on, daughter!
Owen: She's not a daughter, she's a princess.
Me: Princesses are daughters, too. Do you know who princesses' moms and dads are?
Owen: Who?
Me: Queens and kings. And the brother of a princess is a prince. So if Katherine is a princess, who are you?
Owen: Darth Vader?