How do genotype and phenotype differ in humans?

In human genetics, the terms genotype and phenotype represent two distinct but interconnected aspects of an individual's biological makeup.

• Genotype: This refers to the complete genetic constitution of an individual, comprising the specific set of genes and alleles inherited from both parents. It serves as the internal blueprint that defines an individual's hereditary potential.12
• Phenotype: This encompasses all observable and measurable characteristics of an individual, such as physical appearance, behavior, and biochemical properties.3

The fundamental difference lies in their relationship: the phenotype is the final result of the genotype interacting with the environment. While the genotype provides the genetic instructions, the expression of these traits is often modified by environmental factors, such as nutrition or climate. For instance, while eye color is largely determined by heredity, other traits like height or weight are significantly influenced by environmental conditions. Furthermore, not all genetic possibilities are expressed; some genes may be latent, recessive, or masked by epistatic genes, meaning an individual can carry a specific genotype without it being visible in their phenotype.345