Research indicates that even in the case of single gene disorders, the severity and timing of genetic expression are affected by environmental triggers, and that established genetic risks can be exacerbated or become protective in the presence of specific environmental exposures (Shields, Fullerton and Olden 2009). Recent sociological research illustrates how gene environment interactions can potentially shed light on the mechanisms linking the social environment to disease. For example, analysis of data for adolescents in the Add Health Study found that genetic traits interacted with family processes (e.g., daily family meals), school processes (e.g., repeating a grade) and friendship network variables (e.g., friend delinquency) to predict delinquency and violence among male adolescents (Guo and Roettger 2008).
