In genetics, what does the term 'expressivity' refer to?

The term 'expressivity' in genetics specifically refers to the degree to which a particular genotype is expressed in the phenotype of an individual. In other words, expressivity involves the variability in how a genetic trait manifests among individuals who share the same genotype. For example, individuals with the same genetic mutation might exhibit different symptoms or varying severity of a condition; this is a manifestation of expressivity.

Understanding expressivity is crucial because it highlights how identical genetic information can lead to diverse expressions of traits depending on environmental factors, interactions with other genes, and individual biological differences. This concept helps geneticists and researchers understand and predict the range of phenotypic outcomes that can arise from a specific genetic background.