[Barrin92]

>but it's because of the cost of raising children and not the children themselves

that's the equivalent of saying "if I control for skin colour I observe no discrimination". The cost of raising children both financially and in time, is intrinsically linked to raising children.

It is often asserted that spousal relationships suffer from the routine chores that come with raising children, and that is not going away. Don't control for the thing you want to measure.

[gubbrora]

It suggests that "children leads to unhappiness" is a property of how society is currently set up and not a universal truth.