Mendelism and medicine: controlling human inheritance in local contexts, 1920-1960

The rise of Mendelism has often been associated with the development of agricultural sciences and the attempts to improve varieties and select new plants. In contrast, historians have tended to stress the tensions between Mendelism and medicine originating in the influence of eugenicists. The use of Mendel's laws in the context of discussing human inheritance and the transmission of pathologies was nonetheless pervading the medical literature from the 1920s onwards. This paper investigates the dynamics of medical Mendelism by comparing developments in France and in Britain. In contrast to reluctant botanists and zoologists, the elite of the French medical profession was often 'Mendelian'. Mendel's laws have accordingly been integrated into a complex approach to the familial transmission of pathologies, into a theory of pathological inheritance, which combined genetics, germ theory and hygiene. This approach was widely accepted among the paediatricians and obstetricians active in both the eugenics movement and the natalist movement. The career of the pediatrician R. Turpin is a good example of the visibility of this form of medical Mendelism and of its long-lasting impact on genetic research in the country. In Britain, where the social basis of eugenics was not the medical profession, eugenics' claims often clashed with public health and hygiene priorities. Medical Mendelism was in the first place supported and advanced by doctors and scientists participating in the public debates about the care of 'feeble minded' and the classification of social groups. As revealed by the trajectory of L. Penrose this context favoured the linkage between statistics and pedigree analysis, thus leading to the 'Mendelization' of human pathologies. After the war, this Mendelization in turn facilitated the rise of medical genetics as a speciality focusing on genetic counselling and on the management of computable hereditary risks. This comparative analysis thus highlights: a) the influence of local medical cultures on the fate of Mendelism; b) the continuities between the pre-war studies of pathological inheritance and the post-war rise of medical genetics.