I was impressed by this study of economic mobility over many generations in Florence: What’s your (sur)name? Intergenerational mobility over six centuries | VOX, CEPR’s Policy Portal. They make a good case that the richer families stay richer and the poorer families stay poorer regardless of the many other changes that occur in an area.To add to this, VOX reviews it and also references a study done in Sweden that finds something similar (Today’s rich families in Florence, Italy, were rich 700 years ago – Vox).
It’s depressing, but not surprising to me. I suspect that while individuals may rise and fall in terms of economic mobility, specific families work to insure that the wealth acquired is maintained through marriage and inheritance. Worse, conditions for poorer families are such that they can never acquire enough wealth to move them from the lower percentile to a higher one.