Here’s an astonishing story: On Aug. 6, 1945, a man named Tsutomu Yamaguchi was running late to his job at the Mitsubishi headquarters in Hiroshima. When the bomb hit, he was far enough away to survive the blast but not far enough to escape immediate radiation burns. Somehow he found his way on board a train that would get him out of town and back to his family in Nagasaki. He made it home the morning of Aug. 8, just in time — well, you guessed it. He survived both bombings. Remarkably, he recovered, returned to work and went on to father two children. He lived to the age of 93.

Science writer Sam Kean uses Yamaguchi’s story to illustrate the complicated interplay between radiation and DNA. His new book, “The Violinist’s Thumb,” takes the same approach to our genetic code that his previous one, “The Disappearing Spoon,” took to the periodic table of elements. In both books, Kean finds a way to frame complex and terribly important fields of science on a human scale, making them relatable and meaningful.

He introduces us to a Dominican nun, Sister Miriam Michael Stimson, who helped invent Preparation H hemorrhoid cream and whose trial-and-error research contributed to James Watson and Francis Crick’s understanding of the structure of DNA. A photograph shows her bent over her laboratory equipment, a bright light shining into her face, her habit and hood illuminated in the manner of a medieval painting.

In another chapter, we meet a farmer who took a tumor-ridden chicken to a Rockefeller Institute scientist, only to find that the scientist was not interested in saving the bird, but in bringing a swift end to its life and performing an autopsy to determine whether its cancer could have been caused by a virus. (It was.) Kean deploys characters such as these to illustrate key concepts in the study of genetics, such as the use of DNA to trace human evolution or the ways in which our bodies read and make use of the information stored in our genetic code.

He pulls off two neat tricks with this approach. First, he demonstrates that science is itself a kind of storytelling: It is our way of making sense of the world around us, of quantifying and defining our human experience. Science is more than charts and tables and molecules and reactions. It is a messy, human, imperfect effort to translate the intricate workings of our world into a language that we can understand. The elements existed before we put them in a table and gave them names. Our DNA was already formed, combining and recombining, before we drew a picture of it and tried to crack its code. Science is a form of speech that we have to invent, bit by bit, to explain our incremental insights into the forces that govern our existence.

‘The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code’ by Sam Kean (Little, Brown)

Knowing this, Kean lets us follow the story in precisely the way that we — all of us — acquire knowledge in our everyday lives. What I know about cancer is not informed by a textbook, but by a haphazard patchwork made up of memories of my grandmother’s death and my aunt’s survival, the offhand remarks made by the laboratory technician who performs my mammogram, the newspaper articles I read, and the Internet rumors I try to avoid. What you know about bacteria might be a similarly pasted-together amalgam of anecdotes and experiences and stray bits of actual information (the human body plays host to more than 100 trillion microbes!) that float past you and manage to stick.

This wide-ranging, free-wheeling approach mirrors the history of genetic science, as Kean demonstrates. We were breeding animals and domesticating plants long before Gregor Mendel sorted out the notion of dominant and recessive traits through his cross-breeding of peas, and we invented our fanciful notions of how babies acquire their traits before we understood what a sperm and egg could do. (Kean recounts a 17th-century medical report of a Naples woman who was frightened by a sea monster during her pregnancy and gave birth to a baby with scales.) Henri de Toulouse-Lautrec even makes an appearance in this narrative: The painter’s parents were first cousins, which was perfectly acceptable at the time, but the result was a genetic disorder that stunted his growth — he stood under five feet tall — and made his bones brittle.

In a forward-looking final chapter, Kean considers the ethics of cloning (he points out that human clones already walk among us, in the form of identical twins), the implications of a genetic basis for sexual orientation or race, and the astonishing possibility of using DNA like silicon transistors to perform calculations.

More than a user-friendly explanation of scientific principles, “The Violinist’s Thumb” is a thoughtful work of literature that allows all of us — the non-scientists, the reading public — to grapple with the big questions about the history and future of our genetic code.

Amy Stewart is the author of “Wicked Bugs: The Louse That Conquered Napoleon’s Army & Other Diabolical Insects.”