If all data sources indicate that domestic culture is the single biggest differentiator to educational attainment, who are you suggesting we blame besides the stewards of said domestic culture?

Go to school, get good grades, don't borrow money, look after your health, get a job, be polite, pay your taxes - these are all the fundamentals of a good culture and are massively predictive of success. Lots of this advice is millennia old. It's not the role of a liberal government to culturally indoctrinate its people.