As a father, I was interested in the research showing that a family with two girls is ‘happiest’. See here.
Of course, as an economist, I would like to point out that I clearly already knew this and, yes, my wife and I have two girls. Clear proof that rational expectations rules in the King household.
Mind you, some of the findings are at slight odds with our experience. For example, two girls are rarely noisy, help around the house, have few fights or arguments, are easy to reason with, …..
Maybe I need to teach the girls rational expectations theory so they know their side of the bargain.