All in the genes.
Read here; emphasis added:
Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.
One can speculate whether these “common variations” differ in frequency among various ethnic and racial groups and the relationship between that and “cognitive measures.” And such “measures” need not only be IQ. Perhaps one day we can measure genetic links to creativity or to hypocritical dual morality hyper-ethnocentrism. Perhaps the Alt Wrongers can productively speculate which groups’ “stereotypes” of being low and high, respectively, in those metrics
would be most likely supported by genetic studies.