There’s actually a very interesting 1995 research paper that studied the relationship between SAT scores and race and family income.

In every single money bracket white and Asian students outperformed URMs. Perhaps most surprisingly white students whose parents made less than 10k a year performed roughly equal to black students whose parents earned between 60-70k a year.

These numbers are almost 30 years old but id doubt there’s been some massive change. It’s reductive and not accurate at all to boil it down to just socioeconomics. There’s obviously more going on but there’s sadly very little research going on that is not heavily ideologically motivated (on both sides).

Correlation != causation. It could be that people with genes for high intelligence tend to be in high demand on the job market and make a lot of money, and also tend to pass those genes on to their children, which gives them an advantage SAT

That just moves the bubble - what explains income?

What exactly do you mean when you say it is 'explained by' income?

edit: added '?'