Maaike van der Lugt, Hereditary Disease in Scholastic Thought (12th-16th Centuries)

This article argues that, contrary to what is often alleged or supposed, the concept of hereditary disease is a medieval creation. Clearly, ancient medicine already recognized diseases that are transmitted from parents to offspring and sometimes suggested explanations that were physiological, but it did not possess the technical terminology allowing it to distinguish between them and congenital diseases.The assimilation of Arabic medical treatises in the 1230s and 1240s was crucial to the development of such a terminology in the West. However, Western authors went beyond their sources by developing legal analogies, by defining the types of illnesses that are passed by heredity (chronic diseases) and by proposing different causal patterns to account for them. The most articulate medieval discussions, which explicitly distinguish between the hereditary and the congenital, date from around 1320. Nevertheless, the place of hereditary illnesses in the medieval life sciences remained relatively marginal.The central notion was generation, not heredity. Moreover, even though in medical and philosophical writings hereditary illness sometimes acquired a eugenic dimension, the Church did not take them into account; neither as a justification for the laws of consanguinity, nor as an impediment to marriage or as a reason for divorce. Finally, despite some similarities and common sources of inspiration, there were few explicit connections between the notion of hereditary disease and the doctrine of original sin. Because of its universality and the necessity that it pass from one generation to another, the latter reinforced rather than undermined the unity of mankind.