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. To choose to remove variations is to decide that normal is best. (Some of our most beautiful productions have been created by people who under our normal social environment would be considered mentally ill.) To remove variation or introduce variation thus has a literally existential effect on our identity. What does it mean for a process to understand its own instructions?
ethics
It’s possible to issue a moratorium on interventional human genetic research, but China has proven that it probably will not respect that boundary.
There are technologies that allow us to avoid ethical dilemmas; e.g. we can do something like IVF to select embryos with the desired genes rather than aborting embryos with the wrong ones.
technology
CRISPR works amazingly well, but needs more testing and improvements to avoid accidental modifications of other sections of genetic material.
It’s possible that the map from genetic code to phenotype is much more convoluted than we think, and if we modify one gene (coding for high likelihood of schizophrenia) we may inadvertently cause negative effects that are seemingly (phenotypically) unrelated.
That map may also be affected greatly by environment. If the relevant genes simply bring a small likelihood of a deleterious phenotypical outcome, maybe it would be better to simply focus greater interventional attention on that individual rather than trying to remove that genotype from the genome.