What Is Genotype vs. Phenotype?

Genotype refers to the specific genetic makeup of an individual — the particular combination of alleles they carry for one or more genes. Phenotype refers to the observable characteristics that result, in part, from that genotype, such as eye color, height, or disease presence.

Phenotype is shaped not only by genotype but also by environmental and lifestyle factors, which is why two people with similar genotypes can display different phenotypes. Understanding the relationship between genotype and phenotype is central to fields like pharmacogenomics, where a person's genotype can help predict how they will respond to certain medications.

References: medlineplus.gov/genetics; genome.gov