I assume dysgenics (which you’d assume is happening if family size is inversely correlated with education and or income). AFAIK there are some studies that sho

I assume dysgenics (which you’d assume is happening if family size is inversely correlated with education and or income). AFAIK there are some studies that show that dysgenics are at least not the only effect in play (e.g. this study https://www.pnas.org/doi/full/10.1073/pnas.1718793115 https://www.pnas.org/doi/full/10.1073/pnas.1718793115). But I am far from an expert on the topic.