My assumption was that the book would be composed primarily of social psychology woo, like it was the last time I wrote about an opinion piece he did, and therefore would be meaningless scientifically. The title tells you that; cultural writers who like to invoke science in their political war often refer to themselves as 'the reality-based community', self-congratulatory rationalization that borders on postmodernism, and he slyly puts 'deny' and 'reality' in the title of the book - because if you deny astrology or a world government, ideas Democrats love a lot more than Republicans, you must be denying reality. And of course Republicans are psychologically different from Democrats, they are also psychologically different from each other, as is every Democrat and as is every other person different from every other person. Even bothering to make the claim sounds like something he would write for an Oprah audience ('if we'd all just listen to each other...') rather than anyone who understands science...but actual physical brain differences are another matter entirely.
Since Republicanism is a primarily American phenomenon, contending that 50% of American brains are quantifiably different and consistently so enough to be measured and categorized is bordering on pseudoscience. The book only spends a brief amount of time on any physical issues, it is primarily 'science' that consists of surveys of college students used to make sweeping claims about his political opposition, as most thought it would be. But any biology claim at all is certain to annoy the biology community, since it is not evidence-based and makes them all look bad when he claims it is.
Writing on RealClearBooks (a sister site of RealClearPolitics), RealClearScience editor Dr. Alex Berezow tackles the flaws in the methodology and debunks the whole business. I am listed as co-author, I added in a paragraph related to Satoshi Kanazawa and Alex was kind enough to give me half billing, but Alex's key point, as an actual biologist, is that genes play a minor role in everything. Contending that they are any sort of vital component in how people think and vote - political determinism - is silly, no matter how much Mooney tries to couch it in science-y language to puff up the egos of people who buy his book.
Are Republicans Genetically Inferior? By Alex Berezow & Hank Campbell, RealClearBooks