Hermann Joseph Muller (1890–1967) was the founder of radiation genetics and one of the few geneticists who exercised enormous influence upon the successful development of genetics in the first half of the twentieth century. Muller won the Nobel Prize in Physiology or Medicine in 1946 for his earlier discoveries on the induction of genetic mutations by radiation. Muller was born in New York City, to a family of German Catholic immigrants on his father’s side. On the mother’s side, his ancestry was of mixed Episcopalian and Jewish origin. Young Hermann lost his father at the age of 10 and had a difficult life during his early years. Much of his early and middle life was in fact spent in hardship, which was in part due to his inability to get along with others, but also because of his support for the Communist Party as well as his sympathy for the Soviet Union. However, his later years, especially from 1946 onward, when he was awarded the Nobel Prize, were spent in relative peace and stability.