jack and jill bathroom term?

Found solid information on Jack and Jill nursery rhyme origin. What was the origin of "Jack and Jill bathroom" design term.

Public Comments

1. It is called that because it is a bathroom that adjoins two bedrooms -- generally separating the two. And the most common gender in families with two children is one male and one female. Hence, the bathroom usually separated a girl's bathroom from a boy's bathroom. And the original designer of the first J-and-J bathroom had 2 kids -- one named Francis and one named Mervyn.