Relevant, from the article FAQ: "A recent study of Icelandic families showed that the parental allele that is not passed on to the parent’s offspring is still a

Relevant, from the article FAQ: "A recent study of Icelandic families showed that the parental allele that is not passed on to the parent’s offspring is still associated with the child’s educational attainment, suggesting that GWAS results for educational attainment partly represent these intergenerational pathways (Kong et al. 2018). Our sibling analyses yield results that are consistent with this conclusion (see FAQ 2.4)." So, it might just be both environment and the genetic influence both correlating to the same thing, and they admit as much.