"This is a world in which females are bigger than males, and mothers become even bigger for every kid they have and when they grow older the growth rate increase for mothers , so every women wants to have as many kids as possible."
Mom: Children, I have great news! Soon you will have a little sister !
Daughter: What? But if you get bigger, you're not going to fit inside the house !
Mom: That's why we're all moving to an even bigger house !