Heritability is a statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population.

What does a high heritability coefficient mean?

A high heritability means that for all the variation of a certain trait in the population, a large portion is caused by genetic differences. A low heritability means that for all the variation of this trait, more of it is caused by the environment. ... When environmental variation increases, heritability decreases.

What does it mean when heritability is 100%?

Yet obviously environmental factors played a large role in each individual tray, so even if heritability is 100 percent, the environment can have very powerful effects on the appearance of a trait.