http://www.businessweek.com/articles/2013-04-22/how-did-the-worlds-rich-get-that-way-luck
"...Canadian economists Miles Corak and Patrizio Piraino look at how often men end up working at the same company where their father worked, finding that as many as 40 percent have done that at some point. The proportion rises to 70 percent among the top 1 percent in income distribution. This helps to explain why the relationship between the earnings of parent and child is even higher at the top end than it is across the population at large, according to Corak... At any level beyond the local, differences in income due to inequality of opportunity dwarf those from inequality of effort or talent..."