[update 2022-02-09: An earlier version of this article contained flawed logic which has been removed]

[update 2022-02-09: turns out the only flaw in my logic was thinking it was flawed; it appeared flawed but only because it was so subtle]

Many people do not understand why, if IQ is so genetic, the children of high IQ parents, regress to the mean. In fact, I was once told by a commenter on Lion’s blog that if IQ were 100% genetic, no regression to the mean would occur. His logic was we inherit 100% of our genes from our parents, so we should have the exact same genetic IQ as our parents.

But there also might be gene-gene interactions, so some genes might only boost IQ when they’re combined with other genes, so you might inherit only one of these genes from a parent, but without the other, it’s useless.