James Coleman published an influential study in 1966, “Equality of Educational Opportunity”. It found that variation in school quality (per pupil expenditure, size of school library, and so on) had little influence on educational achievement, while students’ family backgrounds did. Which is consistent with genetic influences.
He did find that a student’s educational attainment was related to that of other students in the school – somehow, educational success rubbed off on others. This was often cited as evidence to support policies of forced integration and busing.
But that finding was a mistake – due to a coding error. Which I first thought meant missing a parenthesis in some computer program, but more likely had to do with mislabeling or misclassifying entered data.