Well of course we do.
Having a conversation with 3 about my parents visiting Friday:
Me: So, who is Pop to me?
Three: Your brother.
Me: No, he's not my brother. What is he to me?
Me: Yes, he's nice. But how is he related to me? He's my...
Three/Me (together): DAD!
Me: Now, how about Grandma? What is Grandma to me?
Three: My mom?
Me: No, she's my mom.
Three: Yes, but we share her.