Yankees -vs- Red Sox

A teacher asks her students if they’re Yankees fans. All of the hands go up except for one student.
“Okay, Bobby. What team are you a fan of?”
“The Red Sox.”
“Why’s that?”
“Well, my parents are both Red Sox fans, so I’m a Red Sox fan too.”
“That’s not a good answer, Bobby. If your parents were both morons, would you be a moron too?”
“No, that would make me a Yankees fan!”