AP Photo

In January, the shooting of Gabrielle Giffords produced a half dozen bona fide heroes, including Patricia Maisch, a 61-year-old woman who snatched ammunition out of alleged gunman Jared Loughner's hands as he tried to reload. For good reason, people like these earn our respect and adulation; their grace under pressure strikes us as almost superhuman. Yet as we marvel at their deeds, we're always left wondering about where, exactly, this composure comes from. Do these people emerge from the womb with sanguine looks on their faces, ready to perform life-saving surgery in the next room if necessary? Or is their coolness something they picked up through ...