You and a friend are standing in front of two houses. In each house lives a family with two children.

"The family on the left has a boy who loves history, but their other child prefers math," your friend tells you.

"The family on the right has a 7-year old boy, and they just had a new baby," he explains.

"Does either family have a girl?" you ask.

"I'm not sure," your friend says. "But pick the family that you think is more likely to have a girl. If they do have a girl, I'll give you $100."

Which family should you pick, or does it not matter?