Commentary: It's not all means and genes--socio-economic position, variation and genetic confounding

The article by Johnson et al. makes two important contributions. First, it demonstrates the value of examining variation in health as a phenomenon of interest in and of itself. Secondly, it provides empirical evidence challenging the assertion that the association of socio-economic position and health is due primarily to shared genetic predispositions. Both contributions have important implications for future studies related to socio-economic exposures and population health.