[I received a copy through NetGalley, in exchange for an honest review.]
Some things in this book I already knew (such as the role of the X chromosome when it comes to colour vision, and why many more men than woman are colour-blind). Some others were completely new to me, although also related to the X in general (immune system features, for instance, including autoimmune conditions) and I was glad I could expand on my knowledge in that regard.
The book draws a lot on genetic research, obviously, both past findings and current ones. I found it easy enough to follow, and it didn’t strike me as heavy-handed on the medical lingo, but perhaps it would be a little confusing for someone who’s really a beginner in that area, and therefore would be better targeted at people who already have some basic knowledge about genetics here?
I did find it somewhat repetitive, though (as in, keep the examples for sure, but no need to reiterate so often that a lot of it stems from genetic females having a “spare”), and the narrative style, when it uses examples from the author’s real life to illustrate certain points, wasn’t always very clear. The concept behind it and the way it is at times expressed could also be easily problematic; the term “genetic superiority” is fraught with double-meaning, after all, and I can no doubt see it interpreted in less than savoury ways. So, one has to be careful about how they approach this: it is strictly about the advantages brought by having two X chromosomes rather than one if you’re a genetic human female (or having two Ws if you’re a male bird—same difference), and definitely not about who is “superior, with a hint of who should therefore dominate the other”.
Conclusion: 3.5 stars