The code that makes us — and what happens when we try to rewrite it

The Gene: An Intimate History, published in 2016, is partly a family memoir and partly one of the most ambitious works of popular science of the past decade. Siddhartha Mukherjee, an oncologist and Pulitzer Prize-winning author, weaves his family's history of mental illness through an account of genetics that runs from Gregor Mendel's monastery garden to the present day.

Mukherjee traces a line from Mendel's discovery that heritable traits follow mathematical ratios, through the identification of DNA as the molecule of inheritance, to the cracking of the genetic code in the middle of the twentieth century. The history is full of forgotten figures, wrong turns and moments when the science collided with politics — nowhere more catastrophically than in the eugenics movement, which used a distorted version of genetic thinking to justify atrocities.

The book's contemporary section focuses on gene sequencing and editing, particularly the emergence of CRISPR-Cas9 as a tool for rewriting genetic sequences with unprecedented precision. Mukherjee is careful to separate what is currently possible from what is speculated, and careful also to ask who should make decisions about genetic intervention — in medicine, in agriculture, in the germline.

Running through the whole book is a resistance to genetic determinism. Genes influence identity, health and behaviour, but they do not determine them. Environment, chance and the interactions between genes all matter. The gene is intimate — woven into everything we are — but it is not the whole story.