I see. It doesn't seem like the data used by the linked article provides any evidence for or against your hypothesis. The data here is perfectly compatible wit

I see. It doesn't seem like the data used by the linked article provides any evidence for or against your hypothesis. The data here is perfectly compatible with a contradictory hypothesis: upbringing does not matter and top schools/employers are good at selecting future high performers. I'm not endorsing either hypothesis, but the data here supports the above just as much as your hypothesis (which is to say, not much).