ABSTRACT
In the late nineteenth and the early twentieth centuries, the hereditary susceptibility to tuberculosis (TB) was one of the most discussed topics in the field of human heredity. Remarkably, the complex and substantial debates concerning this topic have left few traces in the historiography of science and medicine. This chapter point outs some of the major methodological developments that emerged in the German context between the late nineteenth century and World War II. In the late nineteenth century, insurance companies were the most important source of data about human heredity. The assumption of a hereditary disposition to TB would remain groundless in the absence of statistical evidence that revealed morbidity rates within affected families to clearly exceed those of the average population. The composition of a hospital population differed markedly from that of a random population. The records featured cases of patients with TB-free children or parents, but they necessarily did not include families that were completely free from TB.
