No, they haven't. Note that all IQ studies are correlational, not causal. You need separated twins to measure causal effects, and there are not enough samples

No, they haven't. Note that all IQ studies are correlational, not causal. You need separated twins to measure causal effects, and there are not enough samples of separated twins. What x% inherited means is that if you plug in parents IQ in a linear regression model predicting child's IQ, the variance error is reduced by X%. This x% correlates with both nature and nurture, i.e. it is not purely genetic. The way that race based intelligence modeling works is by plugging in race as a covariate in the linear regression along with parental IQ and measuring the reduction in variance error. Anyone with any background in statistics knows that there are huge errors in this kind of modeling because of confounding variables. For eg, if we plug in poverty as a covariate then we can expect poverty covariate to reduce the variance error even more. However it will also reduce the assigned x% variance reduction to other covariate, because poverty is correlated both with parental IQ and race. Depending on your agenda, you can stuff in enormous poverty covariates to claim that IQ is primarily affected by poverty or the zip code you are born in OR going the other way, that your race determines your IQ. The fundamental problem is that these are correlational models, not causal. Edit: about twin studies. Heritability of IQ is accepted, though proper causal models haven't been built because there are never going to be enough separated twins. The wikipedia claim about 70% heritability of IQ in twin studies is not actually supported by the cited research. I have directly linked the wikipedia cited research article, which is actually sceptical of correlational studies[1]. " Re- search designs that do not involve total experimental control by the investigator (organisms being bred for specific experimental reasons—inbred strains, partic- ipants being fully randomized to treatments, etc.) are always problematic in that alternative explanations of a finding are invariably possible. This is certainly the case with human twin and adoption studies." [1] http://emilkirkegaard.dk/en/wp-content/uploads/Genetic-and-environmental-influences-on-human-psychological-differences.pdf http://emilkirkegaard.dk/en/wp-content/uploads/Genetic-and-e...