Are you ready to hear something? I want you to see if this sounds familiar: any time you try a decent crime, you got fifty ways you're gonna f**k up. If you think of twenty-five of them, then you're a genius... and you ain't no genius.-Mickey Rourke to William Hurt in Body Heat
In a recent Twitter discussion, wherein I suggested that "Educational Attainment" GWAS/PGS are largely bogus, bolstered by population stratification and assortative mating, someone noted: "Sooo, you'll bet against EA3 explaining even 1% in any new European sample within families?" The implication here is that, despite the many studies coming out lately suggesting the extent to which polygenic scores are subject to stratification issues, if even 1% is explained in a "within family" PGS, then at least something is genetic. This is quite a lowering of the bar from the supposed 13% from EA3 (the third large educational attainment GWAS study), which I assume from some of the recent studies (here and here), they see dwindling away. Anyway, something is better than nothing, so this is a way to suggest "something" is there. Certainly, when looking at "in family" GWAS/PGS, you are going to expect significantly less population stratification, since you are looking at individuals that share the same parents, upbringing and DNA. For example, a recent study showed significant attenuation when looking at "in family" (which surprisingly, considering the authors, they attributed to socioeconomic confounders). Nevertheless, even a smaller percentage is still something and now they might claim, at the cost of a predictive dilution, that they eliminated all stratification issues by using "within-family" analysis. Well, I'm not so sure about that, as I will discuss below the fold.