This book analyses the nature-nurture controversy and recent history and methodology of behavioral and psychiatric genetics. It discusses genetic reductionism, determinism, heritability, "free will," and quantitative and molecular genetics. The philosophical considerations and history of ideas at the heart of this book offer valuable and illuminating context for readers of contemporary genetic studies of behavioral phenotypes. This is a thoughtful, multifaceted, and nuanced work. In sum, Schaffner offers a brilliantly written and useful volume for learning and teaching about behavior genetics, its assumptions, methods, and findings.