Epigenetic Inheritance of Traits: The Impact of stress on the offspring

Abstract

Many people notice similarities in anxiety, fears, or weight gain between parents and children, which raises the question of whether stress leaves biological traces on DNA rather than only being learned. This review asks how external stress affects the epigenome, the collection of epigenetic marks that alter gene activity without changing the DNA sequence, and whether these effects can pass to later generations. Evidence is mixed, and some scientists doubt that such marks can be inherited at all. We critically examined three key studies: historical records linking food availability to health across generations, a cohort of people exposed to famine before birth, and a mouse fear-conditioning experiment, assessing the methodology, strengths, and limitations of each. The historical records showed sex-specific links between grandparental food availability and grandchildren's mortality, but were purely statistical and had small subsamples. The famine cohort found that starvation around conception was associated with reduced IGF2 methylation in adults six decades later, but its small sample limits generalizability. In mice, fear of an odor conditioned in fathers appeared in later generations, but the relevance to humans remains debated. Overall, the evidence suggests that external stress leaves measurable epigenetic marks and that some may be heritable, yet no clear molecular link connects animal models to human data. Future work should test these findings directly in humans with larger samples and molecular analysis.