Two European researchers -- Guido Erreygers & Toon Vandevelde recently published ['98] "Is Inheritance Legitimate: Ethical and Economic Aspects of Wealth Transfers" which you might want to check out. From the US side two of the most recent are "Inheritance and Wealth in America" ed. by Robert Miller & Stephen McNamee ['98] and "Wealth in America by Lisa Keister 
According to research cited in IW in A, there is some controversy over the 20/80 effect which is linked to models of life cycle wealth. Some say 20% of our total wealth is inherited with 80% life cycle accumulation; others saying just the opposite.
One of the big catalysts for trade union militancy in the US prior to WWI was the "Walsh Report" which singled out inheritance and the violation of norms regarding it laid down by Jefferson as the major source of inequality. Plus' a change...
Alexandre Fenelon wrote:
>What about inheritance, which is responsible for 50-75% of the wealth
>distribution in the U.S.?
>This is very interesting, Doug. Do you have the ratings for European
>and Asian countries? And what about inheritance taxes in industrialized
No idea. When I was doing the research for Wall Street, I read the
rather small literature on estimating the effects of inheritance on
wealth distribution. It's extremely hard to get data, since, as they
say, paying estate taxes is almost voluntary. As I recall - it's been
a few years - 50% was a fairly conservative estimate, but 75% was by
no means outlandish. That treats the appreciation of inherited wealth
during the recipient's life as part of the inheritance, by the way.