For the time being, I'll just consider literacy as a binary quality, leaving aside differences in ability. In developed countries, with literacy rates around 99%, literacy is probably some what heritable because that <1% cannot read because of some sort of learning defect with a heritable component.

In Mail, with a 26.2% literacy rate, literacy is not very heritable. The illiterate there are a consequence of lack of educational opportunities. I think that the situation we are in regarding the phenotype of "rational" is closer to the Mali scenario rather than the developed world scenario.