How many more stories do I need to illustrate that, with a little bit of knowledge, persistence and hard work, anybody in an economic free society can climb the money ladder?
Firstly, it is not a matter of pure numbers. Traditionally, in statistics a sample size of n > 30 is necessary in order to generate meaningful results. Second, not only must samples be greater than 30, but in order to be representative (generalizable) participants must also be randomly selected. Any findings drawn from samples failing to meet these requirements are statistically meaningless. This describes your family sample here.
What do you mean by "economic free society," anyway? Is it your view that, just because people are entitled to abstract economic freedom, this means that, in practice, they are literally free from any and all economic constraints?