Blood Groups and Behavioral Genetics: Crime, Insanity, and Temperament

There were relatively fewer studies done on blood group distribution associated with human behavior. Nonetheless, this research which sought to use blood types as genetic markers of abnormal behavior such as criminality and insanity, is telling of some of the pitfalls of research in human biology in the twentieth century. These included pursuing research out of one’s field, extrapolating from too little data, and interpreting data to fit preconceived notions about human behavior. Blood groups also offered the possibility of a relatively simple way of identifying those whose behavior might otherwise appear to be normal. The research was facilitated by easy access to populations for testing in prisons and insane asylums. When it produced negative or insufficient results, rather than ending the search, there was often a call to study more complex definitions of abnormal behavior. Another rationale for further research, despite the lack of direct links between specific blood types and insanity, was that blood testing might indicate a predisposition.