ABSTRACT
Ideas and knowledge about the inheritance of physical and mental characters in humans, whether normal or pathological, form one of the most important elements of intellectual and scientific life of the twentieth century. Anthropological concepts of race and ethnicity continued to have a legacy in human genetics and sociological and psychological ideas regarding class, inheritance and ability. The field of research about human heredity comprises a wide range of practices and ideas that transcend disciplinary borders. Heredity, in a strict biological or genetic sense, was not an age-old concern of humanity. The concept itself only acquired a biological meaning in the mid-nineteenth century through the confluence of independent traditions within medicine, animal and plant breeding, natural history and anthropology. The Mendelian idea of the unit character was attractive for medical scientists and anthropologists alike because it corresponded with a functional definition of physical characters and with a trend towards more precise nosological definitions.
