Studying Jeopardy! contestants in the US, we explore whether and when gender differences in performance in competitive settings and risk-taking emerge with age and by opponents' gender. We identify no gender differences in winning episodes, responding, or responding correctly to clues. Male teenagers (but not children) wager substantially more than female teenagers, leading to the emergence of the gender gap, equivalent to a 7.3 percentage point difference. This gap persists for college students. Finally, male teenagers and college students wager substantially less when competing against females, whereas the gender of opponents does not influence the behavior of young female contestants.