Historical research on the international eugenics movement has gradually moved from outlining its basic aims and political agendas to more detailed accounts of the institutions and practices through which eugenic ideas became political realities. Although historians have repeatedly stressed that eugenics was a science-based movement, they have not always been clear about what kind of science eugenicists were working toward, often leaving it open to question whether the appeals to science were made just to furnish an ideological justification for the eugenic programs, or if scientific theories and practices were in fact the driving forces behind these programs.

In his book Social Mendelism, Israeli historian Amir Teicher sets out to reassess German racial hygiene and Nazi racial policy by investigating how these were shaped by the theory that gave rise to modern genetics – the Mendelian concept of heredity. The basic logic of Mendelian genetics, according to his hypothesis, not only determined the ways in which German eugenicists perceived hereditary disease and “inferiority”, but also influenced the politics of racial persecution in the Third Reich. The title is evidently conceived as a reversal of the term “Social Darwinism”, which, according to Teicher, dominates the perception of eugenic and racist ideas in the twentieth century. This appraisal may come as a surprise to most scholars familiar with the topic. Certainly, many general historical accounts of Nazi Germany employ an (often ill-defined) notion of “Social Darwinism” to describe the fundamental ideological roots of racist policies. It is also true that Mendelian genetics has long been, and still often is, depicted as a scientific concept incompatible with racist thinking and eugenic aspirations. Nevertheless, studies on the topic have long established that Mendelism was essential for the formation and subsequent radicalization of eugenic agendas, especially in its German and North American variants. Gisela Bock – to cite one of the “classic” authors in the field – clearly articulated back in 1986 that the Mendelian genotype-phenotype distinction created a sharp antagonism between the world of appearances and the hidden realm of man’s genetic essence, populated by pathogenic and detrimental elements.¹ While Teicher does not do adequate justice to such theoretical groundwork, he nevertheless delivers on his claim that a Mendelocentric view on Nazi eugenics and racism provides new insights.

Systematically, he pursues the impact of Mendelism on three different levels: as a research tool in the study of human heredity; as a way to popularize and propagate eugenic and racial anthropological ideas (primarily in school teaching); and as a framework for eugenic and racist legislation. Unlike many historians before him, Teicher takes seriously the scientific work of German eugenicists. On the one hand, he offers a close reading of the key studies of eugenicists like Ernst Rüdin and Eugen Fischer that elucidates the technicalities and difficulties associated with a Mendelian view of human heredity. On the other hand, he demonstrates that Mendelian approaches were by no means confined to a small group of notorious authors, but that they were applied to a great number of psychiatric and anthropological problems, at quite different levels of methodological sophistication, and often with inconsistent or conflicting results. Teicher’s comprehensive account of the “Mendelization” of German psychiatry and anthropology, however, is in parts too unambiguous. Mendelism did not simply supersede pre-Mendelian concepts of heredity but coexisted or – more often – intermixed with them. Ironically, in the discourse of early human genetics, Mendelism rarely appeared as a pure conceptual trait, but more commonly in polygenic hybrid forms.

Nevertheless, as Teicher lucidly shows in his chapter on Nazi eugenic legislation, the Mendelian concept of heredity was crucial for a perception of diseases and anomalies as distinct and immutable entities. Unraveling the genesis of the Nazi sterilization law, he demonstrates that its whole architecture gravitated toward the claim that the inheritance of all the anomalies it purported to combat followed a well-known and calculable pattern. The Mendelism that was used to justify the Nazi sterilization campaign, though, was a simplified one: it associated diseases with single recessive, i.e., hidden, genetic traits. Further, it contrasted genetic purity as a norm with genetic variation as an anomaly. It was this notion that also informed the popularized form of Mendelism which Teicher traces through school syllabi and health propaganda. Mostly visualized though the display of trait-markers in pedigrees, it provided a very suggestive picture of why deleterious traits were so insidious, and why they had to be targeted when they surfaced. More importantly, the same perception also conveyed a specific understanding of racial mixture. Whereas pre-Mendelian expressions of antisemitic racism tended, as Teicher shows, to stress that the heritable traits of Jews – or other non-European “races” – prevailed over European ones in cases of “race mixture”, “Jewish traits” now became sneaky genetic threats that made themselves invisible only to reappear after generations. In this view, “racial hybrids” were potentially imposters hiding their true identity. In the central and most seminal part of his study, Teicher expounds how this notion permeated political and legal debates about the treatment of German-Jewish “Mischlinge”, from rank-and-file “race experts” to the highest echelons of the Nazi leadership. While Mendelism was sometimes invoked to argue that by constant interbreeding with Germans, traces of Jewishness could gradually become volatilized within the German gene pool until they no longer endangered it, it mostly served to back the position that Mischlinge were a long-term threat and therefore had to be prevented from breeding among themselves and with “Aryans”.

Teicher does not claim, by any means, that his findings provide us with an entirely new understanding of Nazi racism. Rather, Social Mendelism intends to challenge the idea that sound scientific concepts cannot combine with unsound ideologies or serve despicable political ends. Although rejecting this dichotomy is certainly no novelty in the science studies, Teicher’s agenda is well founded given the perennial recurrence of genetic essentialism and sociobiological speculation which is invariably bolstered up by invoking the pure, apolitical truth of biological science. It would have served his argument well, however, to go more into the dialectical twists inherent in his story. Teicher points up that the Mendelian concept of independent genetic traits undermined the idea of fixed racial types that characterized Nazi racial theories, but he does not further pursue the fact that a significant part of German racial anthropologists abandoned typology for a “population biology” that claimed to provide a comprehensive picture of the selection processes that allegedly shaped society. Likewise, Teicher could have been more explicit regarding the fact that by the time one-trait Mendelism was dogmatized by the sterilization law, the expert discourse had disengaged almost completely from simplistic models. Even advocates of a radical sterilization practice admitted that most problems of pathological heredity could only be understood by applying a “higher Mendelism”, reckoning with complex genetic interactions. In their research, they turned to the statistical approaches of twin research and empirical genetic prognosis, which no longer aimed at establishing clear-cut Mendelian ratios and often yielded results that challenged their initial working assumptions. Even though Teicher’s book does not focus on such incongruities between eugenic or racialist doctrines and the scientific knowledge produced in their support, it nevertheless provides an explanation for them: the imagery of particulate Mendelian inheritance is a powerful thought pattern that has, from its formation up to the present day, sustained and conveyed a basic belief in the omnipotence of heredity, regardless of all the scientific evidence that can be invoked to subvert it.