All ethnically English people descend from Norman conquerors. At least higher than 99% - there might be a few genetic holdouts.

Thanks that sounds fascinating. Will take a look

Actually, that 0.7 intergenerational correlation only tracks surnames—i.e., the male line. It completely ignores the fact that ~50% of the population changes status by marriage, which is invisible in surname analysis. Think about it: when a blacksmith’s daughter marries a baron, her social mobility doesn’t show up anywhere in the data. She just becomes part of the baron’s lineage going forward. So Clark has discovered that patrilineal dynasties persist with 0.7 correlation, and then presented this as if it were a measure of social mobility. It’s not. It’s a measure of surname mobility. If assortative mating across 500 years averaged something like 0.5 (plausible—people married outside their exact status all the time), the actual population-wide status persistence might be closer to 0.4 than 0.7. That’s… a completely different story about how stratified society actually was. But sure, “elites persist for centuries” makes for better book sales than “we measured half the mobility and ignored the other half.”