Mendel did not formulate his findings in the form of a series of laws. This task was left to his followers, who formulated the rules of Mendelian theory in a variety of ways. Following the successful application of Mendelian principles in plant and animal breeding experiments, anthropologists, psychiatrists and genealogists attempted to identify Mendelian patterns also in man. The two scientists who tried most rigorously to introduce Mendelian concepts into their respective fields in the early 1910s – Eugen Fischer (in anthropology) and Ernst Rüdin (in psychiatry) – would later become among the most prominent scientists in the Nazi academic world. Fischer’s work on racial bastardization (hybridization) signaled the path that racial anthropology was to take in future years; Rüdin’s treatise on the Mendelian nature of mental illnesses proved pivotal in shaping later psychiatric thinking. Genealogists tried to similarly devise a genealogical chart that would accord with Mendelian requirements. By the eve of WWI, physical anthropology, psychiatry and genealogy all seemed on the verge of a new Mendelian era.

The rediscovery of Gregor Mendel’s studies on plant hybridization at the beginning of the twentieth century marks the starting point of modern genetic research. Many acknowledge the fact that Mendelism informed early twentieth-century hereditarian and eugenic thinking in Germany and in the US. But the view of Mendelism itself remains that of a mechanical, ideologically neutral, possibly even anti-racist theory. Eugenicists’ adoption of Mendelian thinking is often seen as dogmatic, overtly simplistic and pseudo-scientific. The moral and analytical benefit of using the label "pseudo-science" when discussing eugenics/racial-hygiene and racial science is, however, greatly limited. Mendelism was a sound and rich theory, and the attempts to apply it to the human domain were genuine and serious. It was also a theory with clear social and political implications, which changed its function as the decades passed and as it was appropriated by scholars working in different scientific realms (anthropology, psychiatry, genealogy) and as it moved between the social and the political domains. It strongly imprinted Nazi sterilization and antisemitic policies and had lasting impact well after 1945.

While Social Mendelism certainly gained its most explicit manifestations in Germany under the Nazi rule, many of its underlying assumptions were shared by scholars and social reformers elsewhere. Moreover, the legacy of Social Mendelism did not suddenly disappear with the collapse of the Third Reich. The efforts made by German eugenicists to continue the sterilization campaign in the immediate postwar years attest to the persistence of Mendelism as a legitimizing framework after the war. Moreover, they show that a racial-antisemitic worldview continued to inform eugenic efforts, under the guise of nonideological Mendelian thinking. The story, then, does not sit comfortably within the boundaries of the 1900–1945 timeline. Neither is it a purely German story. There were great national differences in the way Mendel’s theory was received, adopted and applied, and in some nations its influence was marginal. But in others, like the US and Britain, it had great social and cultural impact. Thus, the present image of Mendelism as a no-ideological, possibly even anti-racist theory, is no more than a mirage, consciously construed after World War II in the context of the emerging Cold War politics.