No human bond is as strong as the one between parent and child. It is therefore natural that middle class families should invest much time and effort in improving their children's life chances. But most societies also believe that those born into less fortunate homes should be able to climb the social ladder. Low-earners are more likely to tolerate ever higher incomes at the top if their own children have a fair chance at similar success.

Academic research shows that intergenerational mobility, the extent to which parents' incomes determine their children's, varies across countries and over time. The international picture is well known: in Denmark, Finland, Norway and Sweden socio-economic status is less persistent across generations than in the UK or the US. Mainland European countries fall some where in between these two groups.