Or so claims Megan McArdle. It seems that McArdle read Sean Reardon's NYT article on the growing gap in educational achievement between the wealthy and the rest of America - though based on the internal evidence of her article, it's a little hard to believe she read beyond the first paragraph. It's obvious, she says, heredity and true breeding of IQ account for all the effect. In support of that she cites some stuff she seems to have invented out of whole cloth. In particular, she pointedly ignores all the evidence gathered by Professor Reardon and his students.
I didn't like McA (AKA Jane Galt) even before I found that she had been forged in the Koch brothers version of Mordor, and sent out on the world with more or less only their slime trail by way of credential. Some of her Kochtopus history is documented here.
What Reardon actually found was that the rapidly growing difference in educational achievement with income is closely correlated with both growing economic inequality and increased spending on preschool educational opportunities by the wealthy.