How do you separate the genetic aspects of IQ from the environmental aspects?
Better educated, “smarter,” and better read parents typically expose their children to information, activities, and vocabulary not found in households where the parents are less educated, less exposed to other cultures, or don’t score as high on IQ tests. IQ tests consist of several parts, but largely include a lot of measuring of how much knowledge a person has attained by a specific age, compared to others in that same age group.
Thus the whole thing becomes circular. People who know more score higher on IQ tests, and IQ scores are higher for people who know more. Children raised by people who know more tend to know more. Hence children of people with high IQ as shown by IQ tests tend to raise children who also score high on IQ tests. Genetics may have little to do with it.