In last week's Economist, the Free Exchange column explored the issue of social mobility across generations. In other words, how much are differences in income in one generation attributable to the previous generation and earlier generations? In other words, how much of the income of the readers of this blog is determined by the income of their parents, grandparents etc.? Greg Clark and Neil Cummins have used rare surnames to measure social mobility rates over the long run (i.e., 200 years plus). They find that social mobility is low in the long run as 70-80% of economic advantage appears to be transmitted from one generation to the next. Click here for an overview of this fascinating research. However, the ultimate question is how much of this economic advantage is down to nature and how much is down to nurture?