Wall Street and male testosterone go hand in hand. That’s no secret. This, after all, is the place whose archetypal character is the brash Gordon Gecko. But testosterone may have played an even bigger role in the financial crisis than you might think. According to a new study, men who are most exposed to the testosterone hormone while still in the womb, end up making the best, most profitable traders. That also means that traders are less than rational creatures when it comes to making investment decisions (and helping stoke irrational market bubbles). At the end of the day they’re partly under the influence of sex hormones.