These are notes I made after finishing the book, so they’ll be more heavily weighted toward concepts discussed near the end. The first half of the book was primarily dedicated to a history of genetic research, which I think helped the reader understand the issues discussed in the latter half. playing God It seems like our identity derives from a complicated combination of genes and chance environmental effects. Part of our strength as a species has been our natural variation, and to begin editing the genome is to assume that we can do it better than evolution has done up until this point.