Chunk #16 — Three examples of misspecified models in the G×E literature — Cicchetti et al., 2007: A gene-by-environment or a gender-by-environment interaction?
equilibrium). Thus, females were probably over-represented in the high activity group: there were ~1.7 times more males in the high vs. low activity groups but ~2.9 times more females in the high vs. low activity groups. Investigators controlled for the main effects of gender and ethnicity, but not for their interactions with MAOA activity or childhood maltreatment. Therefore, a potential alternative to their findings is that the effects of maltreatment depend on gender, which presented itself as a MAOA-by-maltreatment interaction in their results. Last, this study also used a mixed-ethnicity sample of African Americans, European Americans, and Hispanics, and given large differences in MAOA allele frequencies between ethnicities (25), it is also possible that the observed interaction was driven by an ethnicity-by-maltreatment or an ethnicity-by-COMT interaction.
