FOR THE past twenty years or so, social scientists have affirmed what parents think when they are at their most exasperated and dyspeptic: children make you miserable. In 2004 Daniel Kahneman of Princeton University and others discovered that parents thought that looking after their children was about as enjoyable as doing the housework. Two meta-studies (studies of studies) in 2012 found that, in most of the research, self-reported “life satisfaction” (a measure of happiness) was a bit lower when there was a child in the house.

The effect was not large. But there is something odd about these findings. In rich countries at least, people decide to have children. A few children are doubtless unplanned but only a few. If children make parents unhappy, why do they keep having them? The puzzle, says Letizia Mencarini of Bocconi University, is why isn’t fertility even lower in countries where people have a choice? Parents far outnumber the childless at every stage of adulthood. A new generation of research helps answer that question, and suggests that children are more likely to make parents happy than was once thought.