In the last decade, scientists across the world have raced to be the first to crack the code of the human genome, exposing a startling new message: at the most fundamental level humans are genetically linked to every part of the natural world. A dog is 85 per cent genetically identical to a human and humans have only twice as many genes as a worm or a fly. For the first time, award-winning science writer Jennifer Ackerman brings together these astonishing discoveries, and by weaving a mesmerising story of heredity, combining both personal memoir with cutting-edge science, she offers an encompassing vision of the impact these findings have on our everyday lives.