The new scientific field, epigenetics, is revolutionizing our understanding of the structure and behavior of biological life on Earth. Epigenetic ideas help explain why mapping an organism's genetic code is simply not enough to determine how it develops or acts, and shows how nurture combines with nature to engineer biological diversity. Surveying some of the key scientific investigations and breakthroughs in this field over the past twenty years, Nessa Carey paints a broad intellectual canvas that readers of science and medicine will find both fascinating and promising. Her book helps us discover how we are much more than the sum of our genetic codes.