For simplicity let’s assume a static equilibrium (i.e. the rate of degree holders doesn’t change across cohorts and people don’t marry outside of their class).

For simplicity let’s assume a static equilibrium (i.e. the rate of degree holders doesn’t change across cohorts and people don’t marry outside of their class). Obviously in such case the probability to get a degree if your parents have a degree are 20% (in 1970) and 66% (in 2020). Now let’s calculate the probabilities to get a degree if your parents don’t have a degree: 1970: 0.04*0.8/0.96 = 3.33% 2020: 0.14*0.34/0.86 = 5.53% Even a “whooping” 1.7 increase doesn’t make much of a difference.