demographers, such as physical weight, may not provide useful information, and the results from GWGEI analyses are also not likely to shed any light on the existing GxE typology, especially given sample sizes in the thousands. Even with a well-established environmental factor and a highly heritable phenotype, we cannot detect overall patterns that consistently support one of the existing models vis-à-vis the others. We were able to find some evidence for each GxE model but no consistent story with biologically plausible mechanisms linking environmental sensitivity to BMI and differentiating the pattern of results from noise. This point is important because it is likely that many of the GxE associations are real, but we simply could not differentiate between real and false interactions with our current methods and data. A SNP-based approach is unlikely to provide empirical results that can be used to support the existing GxE models. We suggest that this typology be reserved for studies focusing on interactions between a candidate gene and the environment (Simons et al. 2011) or those examining heritability by environment interactions (Boardman et al. 2011).
