What genetic term describes the varying nature and severity of the phenotype among individuals?

The term that describes the varying nature and severity of the phenotype among individuals is "Variable Expression." This concept refers to the phenomenon where individuals with the same genotype can exhibit different phenotypes in terms of appearance, behavior, or other characteristics. The severity of these traits can also differ, leading to a wide range of possible outcomes.

For example, in the case of a genetic disorder, some individuals may show only mild symptoms, while others may experience severe manifestations of the condition. This variability can be influenced by several factors, including environmental influences, interactions with other genes, and epigenetic factors. Understanding variable expression is important in genetics as it helps researchers and healthcare professionals predict the impact of genetic disorders on individuals.

In contrast, the other options refer to different concepts: "Phenotype" describes the observable traits of an organism, while "Genotype" refers to its genetic makeup. "Mutation" is a change in the DNA sequence that can lead to changes in the phenotype, but it does not specifically address the variability of phenotypes among individuals.