This book takes aim at the idea that gender inequalities in society can explained by brain structure, as revealed by MRI scans, etc. This 'neurosexism' as Fine calls it used to seem reasonably plausible to me - after all, I'd gone to school with a bunch of girls who claimed they were all about feminism and equality, but they mostly steered clear of science and maths. In retrospect, they were probably not the best people to see if they had been unduly influenced by their society.
One part of the book emphasises how the science part of brain differences between the sexes is badly understood, and nothing like the popsci view. This is a difficult one, because while it's not well understood, there does appear to be something here. The fact that violent crime is so heavily weighted towards males surely means something fairly serious about male and female differences. All the other parents I know seem to go on about how much more quickly the girls are learning to speak. The gender difference in autism rates probably means something. Or maybe, like colour blindness, the rates of occurence don't actually tell you about the main population.
However, gender differences caused by genetic effects on the brain don't matter! This is the point made by the rest of the book, which goes into great depth to show the effects of overt and unconcious sexism, and all kinds of stereotyping, on society. It's bad. I mean, really bad. 'So glad I'm a bloke.' bad. In comparison, intrinsic brain biology effects on gender differences are a drop in the ocean. This is a case she makes convincingly, and it ties in very well with her other book, A Mind of Its Own, and Gladwell's Outliers. The latter explains the historical lack of great female scientists and mathematicians - without the opportunities, intrinsic talent will be wasted, even if it's utterly brilliant.
Throughout the book, the modern 'scientific' approach to explaining gender differences is ridiculed very effectively by quoting nineteenth-century 'scientific' explanations for why the inequalities of those days were inevitable. We still have so far to go. This book is entertaining and depressing in equal parts, but if you think that gender equality is even vaguely near achieved, it's worth reading.