Comes down to the fact that IQ has a high correlation to your offspring's IQ (although regression to the mean happens there) and to your income (although incremental increases in IQs > 130 make no difference to income, the professor effect). That being said, it is clear to see why if your parents make more money you get better SATs. Of course there are other reasons too, like more stable families, more attention (because higher earners have less kids), more access to books, more mathematically inclined parents that can help you on homework, but in general, these things all come back to the parent's IQ.

There is a fairly logical chain of events here, and I'll agree that while not perfect causation this is interesting.

Higher SAT scores generally mean better college education (on average) with more scholarships (enabling less student-loan slavery post-graduation), more grad school, better jobs, etc.

People that got an 800 on their SAT (out of 1600 in my day) weren't really on the fast-track anywhere except mowing lawns. The kids pushing closer to 1400-1600 were generally headed to decent schools.

Yeah, you could interpret it the other way if you wanted to be contrarian. E.g. A rich family is a family with good genes. But that seems like it would be too categorical for a 15% difference (maybe, what's the min SAT score?).

What makes it striking though is that the average(I assume?) test score isn't higher than 580 at the >$200k level. Granted, I haven't done the SAT's in 20 years, but that's certainly not genius territory there.

It leads me to think that the carefully cynical hypothesis is the more correct one. :-) 15% of your SAT score probably measures your _proximity_ to wealth.