Differentiate between broad sense heritability(Hb) and narrow sense heritability(HN)

Broad-sense heritability ($H_b$) is the proportion of total phenotypic variance ($V_P$) that is due to total genetic variance ($V_G$). It includes all genetic effects: additive, dominance, and epistatic interactions.

$$H_b = \frac{V_G}{V_P}$$

Narrow-sense heritability ($H_N$) is the proportion of total phenotypic variance ($V_P$) that is due to additive genetic variance ($V_A$). Additive genetic variance refers to the average effect of individual alleles on the phenotype.

$$H_N = \frac{V_A}{V_P}$$

The key difference is that $H_b$ accounts for all genetic contributions to a trait, while $H_N$ specifically measures the genetic component that can be passed on predictably from parents to offspring, making it more useful for predicting the response to selection in breeding programs.