What makes a billionaire a billionaire? Shrewd investing, innovative ideas, and the ability to adapt to a changing market, sure. All of these are important, but it’s hard to deny that most of the super-successful have a certain something that even the experts have trouble nailing down.

Forbes recently took a stab at exploring what that special something might be. Analysts looked at the 274 self-made members of the Forbes 400 list in search of interesting patterns and trends.

Here are some highlights:

14% of self-made billionaires dropped out or did not attend college. Tech billionaires are particularly well-represented, with tycoons like Bill Gates (Microsoft), Steve Jobs (Apple), Michael Dell (Dell), and Mark Zuckerberg (Facebook).

Billionaires in the finance sector were more likely to hold degrees—and 70% of billionaires with M.B.A. degrees received them at Harvard, Columbia, or the University of Pennsylvania.

But college aside, another finding suggests that many billionaires started learning much younger. A large chunk of billionaires had parents with math-related careers, like engineering and accounting.

Finally, many billionaires experienced major financial setbacks at the beginnings of their careers, which taught them to be more cautious with future investments and ventures.