When Charles Darwin published “On the Origin of Species” in 1859; while the finches of the Galapagos Islands formed an example of natural selection, he also referenced selective breeding in animal husbandry as an example of how desired characteristics in breeds could come about. It did not take a genius to realise that selective breeding could also be applied to humans, although it was one, Francis Galton (Darwin’s half-cousin) the Victorian polymath, who did so and founded eugenics. At a distance of over a century it is difficult to see why they found eugenics so attractive as opposed to other interventions, but late Victorian Britain was a country in the grip of an early version of the Great Replacement theory, in this case the replacement of the educated middle and upper classes with the, then uneducated, working classes simply because the latter were having many more children. Galton’s “Hereditary Genius” set out the case for eugenics: that the ‘better’ classes should be encouraged to breed more and the ‘worse’ classes less.  This idea was attractive to many: Winston Churchill, Arthur Balfour, William Beveridge, George Bernard Shaw, Sydney and Beatrice Webb, Marie Stopes, and D H Lawrence amongst others. It even gained the support of the Manchester Guardian. In 1913 the Liberal Government, including Churchill, passed the Mental Deficiency Act (only 3 MPs voting against) which locked up those of low intelligence in institutions, effectively preventing them from breeding, although it did not require sterilisation. That Act was not repealed until 1959.

By 1913, Galton’s ideas had spread far beyond the UK with the United States, in particular, taking them up vigorously; the Eugenics Records Office at Cold Springs Harbour on Long Island being funded mainly by the Carnegie Institute, Rockefeller Foundation, and the philanthropist Mary Harriman. This should be a warning about letting those with money fund research; their interests may not accord with those of society as a whole. Unlike the British, the Americans had no qualms about sterilising those whom they thought should not be allowed to breed, Supreme Court Justice Oliver Wendell Holmes writing in a 1927 judgement “Three generations of imbeciles is enough”.

Not surprisingly, these American ideas soon crossed back across the Atlantic, this time to Germany, where Alfred Ploetz built on them and the earlier scientific racism of Ernst Haeckel, who had brought Darwin’s ideas to Germany. In time this led to the Holocaust as we all know, but it is important to appreciate that the first victims were those they considered inadequate, either physically or mentally. That experience inoculated most of the world for a couple of generations, but with the success of the Human Genome project and the development of CRISPR gene editing it became possible not only to repair faulty body cells (somatic cells) to cure some rare diseases, but also change the germ cells that create the sperm and ova and so eliminate the disease in future generations. Eugenics was back!

The second part of the book brings the story up to the present and covers what gene editing can, and more importantly, cannot do. It is an important corrective to the idea that genetics at its root is simple: we all learned at school about the heritability of eye colour, controlled by the OCA2 gene. Yet only 62% of those with two copies of the blue-eyed version of the gene have blue eyes; while 7.5% of those with two copies of the brown-eyed version of the gene have blue eyes as well (p. 217). Genetics is nowhere near as simple as people think, and Rutherford offers several other examples.