Debating interaction: the history, and an explanation.

Research on the interaction of nature and nurture now spans nearly a century. (Throughout this article, ‘the interaction of nature and nurture’ or just ‘interaction’ is used to refer to the population-level phenomenon wherein different hereditary/genotypic/genetic groups respond differently to various environmental exposures. I will not be discussing individual-level processes, such as various gene expression mechanisms, where one might say that nature and nurture are interacting.) It has evolved from investigations of strains of crops, to whole genotypes of livestock, to specific genes of humans. It has been performed by a variety of scientists, from epidemiologists and evolutionary geneticists, to developmental psychologists and neuroscientists. It has generated results in the context of eugenic debates about sterilization, social debates about race and clinical debates about treating debilitating disease. What is remarkable, then, is the fact that the debates about the interaction of nature and nurture have remained strikingly uniform during that century. Even as the scientists, the social context and the technology have changed, the same arguments for and against interaction have turned up time and again. In Beyond Versus: The Struggle to Understand the Interaction of Nature and Nurture I aim to explain this phenomenon—to explain why the struggle to understand the interaction of nature and nurture took the form that it did over the past century and how it continues to shape contemporary research on interaction. The book tells the history of debates regarding research on interaction, draws on tools from the philosophy of science to weigh in on those debates and also looks ahead to ethical discussions regarding genetic testing for genes implicated in gene-environment interactions. For the purposes of this target article, I will focus on those chapters which I believe to be of most interest to the International Journal of Epidemiology readers—the chapters from part 1 which trace the history of the debates, from arguments regarding eugenics in the 1930s to disputes between contemporary researchers regarding the causes of depression.