Gene-Environment Interaction

Gene-environment interaction, also called genotype-environment interaction or GxE, occurs when two different genotypes respond to the same variation in environment in different ways, a relationship that can be visualized with a norm-of-reaction graph plotting genes against environmental factors for a continuous phenotypic trait; when the lines on that graph are not parallel, each genotype is responding to environmental variation differently. Environmental variation of this kind can be physical, chemical, biological, or a matter of behavior patterns or life events, and gene-environment interactions are studied across genetic epidemiology, where they help explain why individuals with different genotypes are affected differently by the same environmental exposure, such as fair-skinned people facing a stronger link between sunlight exposure and skin cancer risk than people with darker skin. Developmental psychobiologists also use the concept to understand individual and evolutionary development, and current scientific opinion holds that virtually every trait is shaped by both genetic and environmental differences together rather than by either alone, a position that stands against a strict nature-versus-nurture framing.