Hmm, the numbers in the publications are not stratified. Besides, I am not sure if the father-to-son monetary delta is the only factor to estimate the mobility. The first publication seems to study a broader set of parameters but all of them except the father-to-son thing look secondary.
I wonder what the data would look like for the various strata in the American society.
http://www.epi.org/publication/usa-lags-peer-countries-mobil...