Epigenetics is the study of changes in organisms caused by modifying gene expression – by alcohol, for example – rather than alteration of the genetic code itself. Recent evidence suggests that alcohol can inhibit activity of an enzyme called histone deacetylase (HDAC) in the amygdala, a brain region that is crucial for storing memories and regulating fear, anxiety, and other emotions. New research addresses histone modifications in the rodent amygdala during chronic alcohol exposure and withdrawal.