Well it might be the weather, or the phases of the moon, or it might just be education! If they couldn't read their IQ score would be 0. Obviously the IQ test

Well it might be the weather, or the phases of the moon, or it might just be education! If they couldn't read their IQ score would be 0. Obviously the IQ test questions strive to be about general problem solving, not culturally specific factual knowledge, etc. But it should be just as obvious that strive is all they can do. They just can not be divorced from a while lot of stuff that's learned. Which is why IQ test are very highly correlated with education, they are also correlated with some natural ability, but it's impossible to tell which contributes how much. East Asian along with us East Europeans, come from very rigorous public schools. I've attended public schools in Eastern Europe and Western Europe and the US. And I have Japanese friends, I met when we were both exchange students in a top notch US high school. We were seniors and my Japanese friends and I were amazed how US seniors barely had a 6th grade level of science knowledge in 12th grade. Now do you think my Japanese fiend and I had all that knowledge because of the systems of public education we came from, or because we were both genetically superior to the US kids? So it's possible that fist and second generation Mexican immigrants score lower on IQ tests, because of genetics. But it's much, much, much more likely it is because of a different educational background. Even if the second generation attended the same schools, that doesn't make up for the educational deficit in their home. And importing highly educated immigrants is a great way to reap the benefits of an education you didn't pay for. And important any kind of humans, even illiterate ones, is a good way to grow the economy. Even the lowest of the low buy stuff, and because humanity is so closely related, they are not bringing down the national IQ in the long term. Or rather they shouldn't be, because if your country is a well functioning state it should be able to educated people and reap the economic benefits from that in the long term. If it can't do that, immigration is not your problem, your problem is you're barely able to come out even, and unskilled immigration is just making that problem worse.