Question

Explain the precise meaning of the statement “The heritability of height in humans is 0.85”. In your answer you should indicate what proportions of the total phenotypic variance in height observed in the population is due to genetic variance and what proportion is due to environmental variance. Explain why heritability only tells you something about the population, and can’t be applied to a single individual. For example, explain why it makes no sense to say that a heritability of 0.85 means that 85% of your height is due to your genes and 15% of your height is due to the environment you developed in.

Answer 1

heritability is a concept that describes how much of the variation in a trait is due to variation in genetic factors. heritability is not the proportion of phenotype that is genetic, but rather the proportion of phenotypic variance that is due to genetic factors.

heritability = genotypic variance/phenotypic variance.

phenotypic variance (VP) is due to the sum of three components: environmental variance (VE), genotypic variance (VG), and variance resulting from the interaction of environment and genotype (VGE)

here, 85% of the variation in height in humans is due to variation in genetic factors.

"it makes no sense to say that a heritability of 0.85 means that 85% of your height is due to your genes" because the height is not due to genes, but 85% of the variation in height is due to variation in genes.

heritability describes the variations between the individuals in a population that are caused by both VE and VG, as well as VGE.