The Wikipedia article pointed to [1] cites the heritability of IQ from 0.5 to 0.9, settling in between 0.75 and 0.85. I had always believed it to be 0.5 and was surprised at how heritable IQ is, with 57% to 73% of offspring intelligence being explicable by the parents' IQs. Note that "job performance, income, and literacy" are predicted, to varying degrees, by childhood IQ.

[1] https://en.wikipedia.org/wiki/Heritability_of_IQ