[1] As part of the book's broader critique of hereditarianism and psychometrics, Kamin also became the first to accuse Cyril Burt of scientific misconduct in his twin research.

[2][3] In the book, Kamin states one of its principal conclusions thus: "There exist no data which should lead a prudent man to accept the hypothesis that IQ test scores are in any degree heritable.

He has gone back to the primary sources and demonstrated with a wealth of circumstantial detail that the data they contain cannot support the interpretation that Burt, Jensen and other hereditarians have placed on them.

The psychologist Nicholas Mackintosh wrote that "Whatever reservations one may have about the validity of his many arguments...Kamin has performed a notable service by subjecting the evidence on the heritability of intelligence to searching and critical analysis.

"[8] Economist John Conlisk commended the book for discussing a "broad range of issues" and for paying close attention to the original data, while also criticizing it for its environmentalist bias.