For the whole of history, all cultures, all countries, all societies, have considered the principles of who can reproduce, who lives and who dies. Governments, society, biology, tradition and myriad other factors nudge and steer and compel people away from the freedom to reproduce with whomever they want. Biology and culture are inextricably entwined: each sculpts the other. For just over a century, we have referred to the deliberate crafting of society specifically by biological design with a word that for half of its existence has been regarded as desirable, and for the other half, poisonous: eugenics.

Eugenics is a project with a short history, but a long past. The oldest readers will have direct memories of the Second World War, and how governments tried to exert the most pernicious forces of control on their populations. Eugenics is perhaps most closely associated with the deranged acts of the Nazis and their evil attempts to exterminate not only millions of Jews, but also hundreds of thousands of people with physical disabilities or mental illnesses, or other characteristics such as homosexuality. They were collectively categorized as Lebensunwertes Leben—“lives unworthy of life.”

The escalation of Nazi Germany’s eugenics program to the Final Solution occurred in incremental steps, preceded by years of broader policies aimed at the general improvement of the German people under the guise of Rassenhygiene—“racial hygiene.” The toxicity of the idea of eugenics no doubt emerged from our collective discovery of the horrors of the Second World War, but state-​sanctioned eugenics policies were also implemented in more than thirty countries, and some of these endure in the twenty-​first century. They were espoused enthusiastically by the two great opposing powers of the postwar twentieth century—​the communist Soviet Union and the capitalist United States. Eugenics has always enjoyed bipartisan support.

Eugenics is in many ways a defining idea of the twentieth century. It was enacted as policy by the most powerful and populous countries on Earth and fueled tyrannical regimes that tore the world apart with unprecedented vigor. Before that though, eugenics was a guiding light for the betterment of Western societies, viewed as normal and desirable by people across political divides, and forcefully championed by the most powerful men and women in society. Winston Churchill was a key driver of eugenics policy in the United Kingdom in the first two decades of the twentieth century, as was Theodore Roosevelt in the United States. Margaret Sanger, a pioneer of reproductive rights for women, advocated for eugenics policies, as did the scholar W. E. B. DuBois, as a potential mechanism for racial uplift for Black Americans.

Many playwrights, suffragists, philanthropists and philosophers, as well as more than a dozen Nobel Prize winners, embraced the ideas of eugenics as a force to change society, some with an almost religious fervor. The first part of this book is a history of an idea that hid in plain sight, from its roots in key philosophical texts of the classical world, in obscure and popular scientific books, and all the way into its genocidal realization in the twentieth century.

It’s difficult for us to comprehend, only a hundred years later, quite how ubiquitous this idea was in the early decades of the twentieth century.

It’s difficult for us to comprehend, only a hundred years later, quite how ubiquitous this idea was in the early decades of the twentieth century. But the evidence is right in front of us, baked into our culture and literature. Novels such as Aldous Huxley’s Brave New World or H. G. Wells’s The Island of Dr. Moreau are tales about genetic manipulation of human life, and the scientist and eugenicist Julian Huxley (brother of Aldous, friend of Wells) even advised on the 1932 film adaptation of Moreau, entitled Island of Lost Souls, for its scientific accuracy. Eugenics percolated through culture in less obvious and overtly fantastical ways too.

A seam running through The Great Gatsby is the then popular pseudoscientific fear about the replacement of ruling classes by less desirable members of American society—​immigrants, African Americans, Irish, the poor—​an idea that fueled much of the development of eugenics policies in the West, and persists among White supremacists to this day. “The Jews will not replace us!” screeched hysterical Nazis in Charlottesville, Virginia, in 2017, in full view of the world’s media, though it was never clear whether they imagined that they were to be replaced by Jews, or that Jews were orchestrating their replacement. Either way, the long-​standing fantasy of the threat of population replacement is part of the elusive promise of eugenics—​to exert control on who lives, who dies and whose people should be preserved.

The cultural ubiquity of eugenics even extends to our food: John Harvey Kellogg was the effective creator of the cornflake, and with those cereals reinvented breakfast for large parts of the world. Many readers will have eaten a dried cereal crop this morning (with a splash of milk enabled by your lactase persistence mutation) whose evolution began with Kellogg’s weird, obsessive desire to control libido with bland fo