"With...many people saying that 'this is proof positive...'" is bullshit. You don't have many people saying exactly that. I don't think you even have one person saying exactly that, other than Lucy. Many people? Which people, and where? In Japan? In America? Did you count them? Weasel words, trying to lend credibility to the Lucy's claim that this is proof positive (!) that nature cannot overcome nurture (!). Third clause of this whopper: people who are born into poverty are doomed to stay there. Wow. You know, I'm not altogether sure that the prince-born pauper is actually poor. Going by what we know, he has a job as a truck driver, which is more than can be said for his mother, who was on welfare, and formally poor. He simply couldn't go to high school or college. In other words, he moved up a bit in life, though granted, not much.
And as rayiner pointed out, this is a single data point. It proves nothing.
Now, what if it did prove exactly that nature cannot overcome nurture? This would mean so much! Suddenly, so much of the progressive agenda would be validated! It would truly be bigotry, and literally nothing else, that was responsible for minorities in perpetual plight. It would truly be sexism, and literally nothing else, that was responsible for how many fewer women are CEO's. It would be a rallying cry for the communists of the world to unite against the pure, distilled evil that etcetera.