She wrote this convincing essay on happiness and parenting.  Parents seem to be less happy but we shouldn’t read too much into that.  She brings together all kinds of economic theory and data and along the way she cites a paper I like very much by Luis Rayo and Gary Becker:

Nobel Prize–winning economist Gary Becker, writing with Luis Rayo, has argued this contrary position. In their view, while “happiness and life satisfaction may be related to utility, they are no more measures of utility than are other dimensions of well-being, such as health or consumption of material goods.”[5] Or having kids. Children may make you less happy, but still raise your utility. Devout neoclassical reasoning leads Becker and Rayo to infer from the fact that we are having kids that they raise your utility (or at least they raise the utility of those who make this choice).

Rayo and Becker argued that happiness should be thought of as the carrot that gets us to make good decisions.  But happiness is a scarce resource.  There’s a limit to how happy you can be.  So it has to be used in the most economical way.  In their theory the most economical way to use happiness is to give an immediate, and completely transitory boost of happiness to reward good outcomes.  You have sex, you get rewarded.  It results in conception, that’s another reward.  But then you are back to the baseline so as to maximize the range available for further rewards (and penalties) motivating behavior going forward.  Bygones are bygones.

With that theory it makes no sense to look at a cross section of the population, compare how happy are people who did X relative to people who didn’t do X, and conclude on the basis of that whether its good to do X.

And by the way, if there is anything we can expect evolutionary incentives to have a good handle on, its whether or not to have kids.  That’s the whole ballgame.  If happiness is there to motivate us to succeed evolutionarily then you better have  a good argument why Nature got it wrong.  One place to look might be on the quantity/quality tradeoff.  Perhaps the relative price of quality versus quantity has declined in modern times and Nature’s mechanism is tuned to an obsolete tradeoff. If so, then people feel a motivation to have more kids than they should.  The prescription then would be to resist the temptation you feel to have another kid and instead invest more in the ones you have.  Unless you want to be happy.