Huh?

Mom: Where does that tall skinny boy live?

Me: He lives here with us. He's my son, Clark.

Mom: Oh, he is? I didn't know that.

Me: Yep, he is. He's also your grandson.

Mom (with a tone of voice indicating that she thinks I'm ridiculous): Well of course he is, if he's your son. (pause) So then...is he related to you?

It's conversations like these that make me wish I understood her brain better.