Mom and Dad have four daughters and each daughter has one brother How many people are in the family?

I don't see why this matters, but there are 10.

Sorry to break it to you, but it's actually seven. If it was ten, each girl would have four brothers, not one.

My mistake. It is seven. Since all the girls are sisters, there is only one brother between them (since he is all of their brothers) 2+4+1= 7 ^^