Heritability (h2)

• Heritability determines the degree of resemblance between parents and offspring, which in turn determines the response to selection.
• In particular, the slope of midparent-offspring regressions just h2= VG /VP.
• The total phenotypic variance (VP) is the sum of genetic variance (VG) and environmental variance (VE).
• Thus, the heritability is the proportion of genetic variance within phenotypic variance.

In wider sense the genetic variance can be separated into dominance (VD) and epistasis (VI). So the total genetic variance is

VG = VA + VD + VI

and that total phenotypic variance

VP = VG + VK = VA + VD + VI + VK

The range of heritability is from 0 to 1, or from 0 to 100%.