the conclusion of the new, high-power GWASs was that, with a few very rare exceptions, complex human traits are generally related to many thousands of genetic variants, each of which appears to contribute only a minuscule effect.59 There was no space for large effects of single genes, which was completely at odds with the results of all those previously lauded candidate gene studies. Since then, efforts that specifically tried to replicate the candidate gene studies with high statistical power have produced flat-as-a-pancake null results for IQ test scores, depression and schizophrenia.
