"This suggests that academic success is shaped by structural forces similar to those that govern social mobility, where the advantage of having a top mentor can lead to a self-reinforcing cycle of success"
This is not surprising. Poor or rich, if you have good family support, you have a much better chance at success. This can be seen with rich kids with absent/uncaring parents blowing all of their money within a couple of years/going to jail/becoming alcoholics or drug addicts.