Mean reversion is relative regression. For example, a child born to highly intelligent parents may not be as intelligent as the previous generation, while a child born to low-intelligence parents may surpass them in intelligence. I once saw a statistic: the probability of a child whose parents graduated from 985 universities also getting into a 985 university is less than 20%. Of course, this 20% probability is still very high compared to other groups, but it still falls far short of expectations.