Genetic vs. heritable trait

When someone tells you that height is 80% heritable, does that mean: a) 80% of the reason you are the height you are is due to genes b) 80% of the variation within the population on the trait of height is due to variation of the genes The answer is of course b. Unfortunately in the 5 years I’ve been blogging the conception of heritability has been rather difficult to get across, and I regularly have to browbeat readers who conflate the term with a. That is, they assume that if I say that a trait is mostly heritable I mean that its development is mostly a function of genes. In reality not only is that false, it’s incoherent. Heritability is addressing the population level correlation between phenotypic variation and genotypic variation. In other words, how well can genetic variation work as a proxy for phenotypic variation? What proportion of ...