Working-class parents in America, for their part, lack the wherewithal to engage in such intensive parenting. As a result, social divisions from one generation to the next are set to widen. Not so long ago the “American dream” held out the prospect that everyone, however humble their background, could succeed if they tried hard enough. But a recent report by the World Bank showed that intergenerational social mobility (the chance that the next generation will end up in a different social class from the previous one) in the land of dreams is now among the lowest in all rich countries. And that is before many of the social effects of the new parenting gap have had time to show up yet.