But why? What are the CAUSAL relationships between parental earnings, educational attainment, and child earnings? The children of doctors are more likely to become doctors, but saying that educational attainment is therefore less related to doctoring than parental occupation is obviously a bit absurd. Just because a parent paves the path doesn't mean that educational attainment is irrelevant to walking that path. And anyone who makes it through med school and residency has the option to enjoy high earnings, regardless of parental income.
The MD example, for the curious and humble reader interested in Truth rather than Winning, makes it abundantly clear why section 3.6 of the linked paper asks a question that's directly relevant to untangling these causal links.
> Do you have another study?
There's an entire literature base on exactly this question. "lifetime earnings parental earnings education" returns 130K results on Google Scholar. But, to be blunt, I don't think you're interested in learning anything. I think you're interested in Winning the thread. So I'm not posting for your benefit; that would be futile. I'm posting for the benefit of intellectually curious readers.