How To Argue With A Racist, by Adam Rutherford.
I think a slightly misleading title as the book is about genetics. However, it is a fascinating and enlightening read.
The author does a good job of explaining a complex subject —I didn't understand everything, but I've come away with some mind blowing facts. Here's one: '...two San people from different tribes in southern Africa [are more genetically diverse] than a Briton, a Sri Lankan and a Maori' (p.59).
To summarise the book; genetics is far more complex and nuanced than fits the simple arguments many racists used to assert their points