> I think a less contentious interpretation is that this data simply supports the theory that intelligence is mostly hereditary. And that a predisposition for intelligence can account for both the parents' as well as their offspring's high earning potential.

As someone with kids in kindergarden and grade school, it's rather visible that 99% of the advantage 1% parents give kids is simply the will to do anything at all. In most kids, there is no such impulse present at all, and it is painfully obvious what the results will be, barring huge behavioral changes. Or at least this is rather obvious in kids whose parents are doctors or lawyers, something along those lines. Less so for kids with manager parents, but still, I do think I see a difference in attitude.

It's not intelligence that's hereditary, it's the 1% more effort (usually more like 100% more effort), that when sustained over 10 years will completely overwhelm any innate intelligence advantage that may be present.

Yes rich parents also give kids more means to accomplish things and that certainly also helps. No student debt, maybe even a house to live in ... certainly helps (frankly, a way to opt out of our financial "services" industry is what makes the difference). But this advantage is useless unless the extra effort is also present.