Comment by dredmorbius

"The richest families in Florence in 1427 are still the richest families in Florence"

“The top earners among the current taxpayers were found to have already been at the top of the socioeconomic ladder six centuries ago,” Barone and Mocetti note on VoxEU. The study was able to exploit a unique data set—taxpayers data in 1427 was digitized and made available online—to show long-term trends of economic mobility.

<https://qz.com/694340/the-richest-families-in-florence-in-14...>

The question is how much ones starting position (that is, birth conditions) predict adult-period wealth and status. Yes, there's clearly movement within ranks, and more at the very top of the rankings than most. But familial wealth trends are empirically quite strongly rooted in status-at birth, from this and numerous other studies.