What is heritability (h2)?

What is heritability (h2)?

• A. The proportion of observed variation due to genetics.
• B. The proportion due to environment.
• C. The average genetic value.
• D. The correlation between relatives.

Answer: (A)

Heritability describes how much of the differences you see in a trait among individuals in a population are due to genetic differences, not the environment. It is expressed as a ratio: h^2 = Vg / Vp, where Vg is the genetic variance and Vp is the total phenotypic variance (Vg plus Ve and other components). This makes it a population parameter that depends on the specific population and environment being studied. A high h^2 means genetics accounts for a large portion of the observed variation, so selective breeding can be more effective; a low h^2 means environment or other factors play a bigger role, making selection less predictive. It does not describe the destiny of a trait in an individual, nor is it the average genetic value. It also isn’t simply the correlation between relatives, which is a related statistic used to estimate heritability rather than being the definition itself.

Heritability describes how much of the differences you see in a trait among individuals in a population are due to genetic differences, not the environment. It is expressed as a ratio: h^2 = Vg / Vp, where Vg is the genetic variance and Vp is the total phenotypic variance (Vg plus Ve and other components). This makes it a population parameter that depends on the specific population and environment being studied. A high h^2 means genetics accounts for a large portion of the observed variation, so selective breeding can be more effective; a low h^2 means environment or other factors play a bigger role, making selection less predictive. It does not describe the destiny of a trait in an individual, nor is it the average genetic value. It also isn’t simply the correlation between relatives, which is a related statistic used to estimate heritability rather than being the definition itself.