The paucity of well-developed and articulated causal models in epigenetic studies is endemic in this literature, and has had several consequences. These include: 1) absent or inappropriate specification of environmental exposures antecedent to epigenetic modification, 2) inappropriate adjustment for confounding by environmental or genetic factors associated with both epigenetic modification and outcomes, and 3) lack of attention paid to the temporal relationship between epigenetic modification and outcomes.
