To be brutally honest, we’re reluctant to have more children because we think that the pain outweighs the gain.
This book is targeted at people who feel some interest in having a child - or another child - but think raising the child well would be more work than they really want to sign up for. The title’s a bit inaccurate: Caplan is mostly trying to convince you that the downsides of having children are exaggerated, not sell you on the upsides. He argues that contemporary society encourages parents to stress over their children’s upbringing to a degree that isn’t really worthwhile.
To make this point, he mostly relies on research on twins and adoptees that indicates parenting styles have little or no long-term impact on a variety of aspects of children’s lives, including life expectancy, overall health, intelligence, happiness, conscientiousness, and income.
Some reviewers misinterpret the argument to be more extreme than it is. As noted in the book, “research focuses on middle-class families in First World countries”; the claim is not that parenting styles and childhood environment are irrelevant, it’s that the differing styles and environments seen in middle-class First World families lead largely to similar outcomes (and thus, that choosing one of the more labor-intensive parenting styles from this range is probably not worth it). To use one of his examples, it’s an argument against forcing your kid to take karate lessons against their will, not an argument for child neglect.
I wouldn’t want to make any drastic decisions on the basis of these studies, but they do seem like a useful caution against having too much anxiety about being a ‘perfect’ parent.
Some of the most interesting caveats noted in other reviews include potential sampling bias due to the reliance on adoptive parents and twins; inability to measure the success of very uncommon parenting styles; potential failure to detect indirect inheritance of mental traits (i.e. a father’s alcoholism influencing a son’s gambling); potential failure to detect combinations of small influences.