The essays in this collection examine how human heredity was understood between the end of the First World War and the early 1970s. The contributors explore the interaction of science, medicine and society in determining how heredity was viewed across the world during the politically turbulent years of the twentieth century: Part I: Constructing Surveys of Heredity Part II: Blood and Populations Part III: Human Heredity in the Laboratory Part IV: Understanding and Managing Disease Part V: Reconstructing Discipline(s).