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Strikes me as the most likely place for finding anything empirical. Using the search term "political dynasties"at HNN, I came up with these results:
http://hnn.us/results.php?cx=009765591100091698464%3Ave6wzf7owyw&cof=FORID%3A11&q=political+dynasties&sa.x=9&sa.y=10#818
Didn't begin to read them all. Other search terms might or might not yield something as well.