to those downvoting this comment -

your IQ test results might as well be your zip code

for a proper explanation, check out Bell Curve by Shaun

for a personal interpretation & in large part summary of the above material:

IQ tests are not a general smartness tests, that is impossible to measure. IQ testes measure your ability to solve logic puzzles, and that supposedly measures your logic itself (at least the tests that have no cultural bits, the ones that include cultures also have some testing of your memory based largely on your country’s school curriculum. more on why that’s a problem later)

can someone be naturally amazing at logic? of course, they can, but that skill needs to be nurtured, or at least allowed to flurish. and this is supposed to happen in schools.

now what happens when a person with the potential to score high in an IQ test doesn’t enjoy the privilege of peaceful learning? what happens when their family life is difficult? what happens when during their schooling years they have to focus on surviving, instead of learning and nurturing their skills? well, they score lower, of course. their potential doesn’t disappear, but it gets used in a different direction, to help them survive in life. and logic puzzles don’t play a big role in survival so that particular skill is not tended to and therefore doesn’t develop as well as it could in ideal circumstances.

now let’s look at racism. we’re not talking about day to day racism, though that also plays a part, but institutionalised racism - the one that keeps pushing minorities into poverty, and keeps them there harder than white people, because as we know, poverty is a trap that’s difficult to get out of even for those not pushed into it with institutional racism.

add the two together - IQ tests measure your logic puzzle solving skills, which develop only if you have access to decent schools & you’re allowed to learn without interruptions, without having to worry for yourself or your family. institutionalised racism pushes minorities into poverty, which means they lose access to good schooling, and have to worry for themselves and their families from an early age.

this in turn results in minorities scoring lower on those tests, but not because they are stupid, but because their intelligence has to be used for surviving, and they are not allowed to comfortably indulge in solving logic puzzles to develop the skills that IQ tests look at to “measure intelligence”