In this context, Chris Dillow has an excellent post which highlights the role of plain good luck in income inequality. He points to a paper by Daniel D. Schnitzlein who compared the earnings of siblings and found that that share of inequality in permanent earnings that can be attributed to family and community factors shared by brothers are 20%, 43% and 45% for Denmark, Germany and US respectively.
Chris Dillow argues that while inequalities that are a result of the individuals' free choices about how hard to work, save and study are acceptable, that arising from the luck of what type of family we are born into is not acceptable. He advocates taxation of those excessively lucky to normalize incomes and remove the inequality arising from their disporportionate good luck.
However, if the objective is to reduce inequality, mere taxation will not help. I have blogged earlier about the work of Lane Kenworthy, who has examined the impact of various government policies on inequality across the developed countries. He has found that contrary to conventional wisdom with its emphasis on progressive taxation system, inequality reduction is achieved more by government transfers and better quality public services, both of which require higher quantity of taxes.
The over-sized role of the "ovarian lottery" in determining life-time incomes is validated empirically by the persistence of inter-generational earnings divisions between people at different levels in the income ladder. In this context, Markus Jäntti, Bernt Bratsberg et al write about the low social mobility in the US,
"Mobility is lower in the US than in the UK, where it is lower again compared to the Nordic countries. Persistence is greatest in the tails of the distributions and tends to be particularly high in the upper tails: though in the US this is reversed with a particularly high likelihood that sons of the poorest fathers will remain in the lowest earnings quintile. This is a challenge to the popular notion of 'American exceptionalism'. The US also differs from the Nordic countries in its very low likelihood that sons of the highest earners will show downward 'long-distance' mobility into the lowest earnings quintile."
Talking about inequality, Joseph Stiglitz has an excellent article in Vanity Fair, where he describes the American democracy as that "of the 1%, by the 1%, for the 1%"! He points to the extreme polarization of income levels in the US - the upper 1 percent of Americans are now taking in nearly a quarter of the nation’s income every year, while the top 1 percent control 40% of wealth.