Spoiler for Series are not my strong point...
>The number of people in the society is not specified either. I assume, there are n married couples.
Spoiler for my calculation
I think there is a discrepancy with bonanova's answer because...
Sure. The gender distribution within families is terribly skewed.
- A family can have an unlimited number of boys; a family can never have more than one girl.
- A family can have a girl with no brothers [half!]; a family can never have a boy with no sisters.