This book was well written and appeared well-researched and thorough for the most part. There was a wealth of information, and I particularly liked the biological perspective on eugenics. I often hear eugenics addressed in moral and social terms, while the bad science behind it goes unmentioned. I have two major issues with the book, however.
First, Carlson includes a couple blatant Biblical inaccuracies that, to a certain extent, cast doubt over the accuracy of the whole book. In his section on the Jews, Carlson writes, "Abraham's two and two concubines produced 12 sons, 11 of them forming scattered tribes and the 12th, Joseph, founding the state of Israel." In fact, Abraham had one wife and one son, Isaac, who himself had one son, Jacob (known as Israel), who had those 12 sons, all of whom became part of the nation of Israel, which was not founded by Joseph. He also quotes a saying of Jesus, that a bad tree does not produce good fruit, as referring to heredity, when any Christian could tell you he's talking about a believer's faith and works (fruits). This is Sunday-school level stuff.
Also, the book seemed somewhat disjointed. The chapters were self-contained packets of information, with lots of names and compressed biographies, and I didn't get a good sense of how these people and ideas interacted with each other. The first few chapters, on Biblical ideas and (...), never really come up again. He also jumped around in time quite a bit, so it was hard to pinpoint any development or narrative in the ideas and culture surrounding them. I have more information now, but the book did not put it in enough context.