Britain's Private Schools Makes a Point About Population Stratification

This article about the British private school system is not directly related to genetics, but goes to a point I've made earlier about genetic studies of "Educational Attainment" and how they will inevitably be filled with false positives related to population stratification.  Let me start with a quote from the article:

What particularly defines British private education is its extreme social exclusivity. Only about 6% of the UK’s school population attend such schools, and the families accessing private education are highly concentrated among the affluent. 

So we have a closed off group that has better access to higher educational opportunities, and of course there is a big payoff for them as we can see here:

The statistics also tell a story. The proportion of prominent people in every area who have been educated privately is striking, in some cases grotesque. From judges (74% privately educated) through to MPs (32%), the numbers tell us of a society where bought educational privilege also buys lifetime privilege and influence. “The dogged persistence of the British ‘old boy”’ is how a 2017 study describes the traditional dominance of private-school alumni in British society.  

What we see here is effectively an aristocracy.  People of these groups tend to marry others of the same privilege and, as the article points out, this has been going on for generations.  How hard is it to see that we then have a closed genetic group?  When anyone utilizes the UK BioBank, for example, to do genetic studies on something like educational attainment, they will of course find numerous genetic similarities amongst those who are most educated.  That is by design.  The idea that any of these people are somehow genetically superior in a way that conveys better educational attainment, requires someone to ignore the evidence of their own eyes when meeting individuals of the upper class.
What we are seeing are genetic markers, little different than those used by Ancestry.com and 23andMe to determine someone's racial heritage and no more likely to identify actual genes related to educational attainment than genetic variants amongst Asian people cause them to use chop sticks in greater proportion than those with European genetic markers.
Thus, when Robert Plomin suggests that elite school admissions be based on polygenic scores he is simply promoting a kind of genetic aristocracy.  There are simply no genes or genetic variants for "educational attainment." The idea is absurd on its face.