The "heritability" of income and CI

In this note, Minkiw analyzes the economic mobility with 2 examples. the first one illustrates the relationship between parental income and that of their children. It is well known that if your father had high income, you are more likely to hace high income than if your father had low income. He mentioned a study which says that the elasticity is 0.5. Which, according to Mankiw, is less than expected.

He Compares this "heritability", as he calls it, with the heritability of intelligence quotient (IQ). Is usually estimated to be much larger this relationship tham the income one.