As a 2-year-old, Nathaniel Lampros, of Sandy, Utah, was fascinated with toy swords and loved to duel with Kenayde, his 4-year-old sister. But inevitably, he'd whack her in the head, she'd dissolve in tears, and Angela, their mother, would come running to see what had happened. She'd ask Nathaniel to apologize, as well as give Kenayde a hug and make her laugh to pacify hurt feelings. If he resisted, Angela would put her son in time-out. "I worried that Nathaniel would never ou