Heritability is a key concept in genetics that helps us understand how much of the variation in a trait (like height, IQ, or risk for depression) among people can be explained by differences in their genes. Here’s an easy-to-understand overview:
Suppose researchers find that the heritability of height in America is about 80%.
This means that 80% of the differences in height between Americans can be statistically attributed to genetic differences, given the present environments.
It does not mean that you get 80% of your own height from your genes and 20% from environmental factors like what you eat.
Heritability helps scientists figure out where to look: if it's low, focus on environment; if it's high, genes are important—but the environment still matters a lot in shaping outcomes for everyone.
This means heritability statistics tell us about the statistical association between genetic differences and trait differences within a certain population and environment—they do not prove genes directly cause the trait in a simple, one-way fashion. ⬅️