It was not until 1933 that a required course in genetics was added to the curriculum of an American medical school at Ohio State. Six years earlier, Lewellys F. Barker, Professor of Medicine at Johns Hopkins Medical School, has written that it was "little short of amazing that American clinicians have been so little influenced either in work or in thought by the stupendous advances that have been made in our knowledge of heredity since the turn of the century."
Some reasons are easy to find. The spectacular discoveries regarding the infectious diseases and the great strides that were being made in sanitation (especially the control of milk and water supplies), in preventive immunization, and later in chemical inhibition of microbes naturally emphasized environmental aspects of medicine. The response of the host, whether fundamentally sound or genetically abnormal, to challenge such as infection or psychological stress went largely unnoticed. The