Because of the hormones they produce.
mama cells and daddy if mama give you more than dad you are a girl if dad give you more than mom you are a boy
They just say what comes first alphabetically. "B" comes before "G" so it's boys and girls club.
They are often used in classrooms to avoid talking.They are often called seating plans, and are a good idea; espeically when the boy, girl, boy, girl is used; its meant to be especially effective if...