your study is from 2012, newest research found strong correlation between certain genes and educational attainment, stronger than environmental factors like parents income[1]

your snopes article is about inheriting from mother alone, not parents

There IS also a significant difference between births based on income

https://www.statista.com/statistics/241530/birth-rate-by-fam...

65 births per 1000 women vs 43 births per 1000 women

[1] https://www.nytimes.com/2018/07/23/science/genes-education.h...