Genetics and Intervention Research.

As part of this special section on genetics and behavioral intervention, we discuss the articles by McGue, Osler, and Christensen (2010, this issue) and by Davey Smith (2010, this issue). In the second half of the present article, we consider the integration of genetics and intervention research more broadly. The two articles describe ways to use genetic controls to infer causation from correlational ("observational") data without intervention. McGue et al. discuss the use of twins discordant for exposure, which is a variant of the cotwin control method. This method can show that the link between an exposure and outcome is not entirely mediated genetically. Davey Smith discusses a method called Mendelian randomization that uses DNA to draw causal inferences without the need for experimental intervention. Despite the possibilities for using genetic controls to infer causation from correlational data in order to attenuate the need for intervention studies, we are most excited about the opportunities for integrating genetics and intervention research, especially as new DNA technologies make it possible to incorporate genetics in any intervention research.