D'Aloisio's parents came to England from Australia. His father, Lou, has worked in commodities for BP and Morgan Stanley, while his mother, Diana, is a corporate lawyer who also serves as her son's contractual representative. They always knew D'Aloisio was an extremely inquisitive child. 'But he was our first, so we didn't think it was anything out of the ordinary,' says Diana. (D'Aloisio's brother, Matthew, is 14.) They stress that despite his impressive accomplishments, he remains a normal kid. Or at least as normal as a kid can be when he's making offhand references to Markov models and stochastic processes. 'He still goes out on weekends, still goes to parties,' says Diana. 'He's got a girlfriend. All the things you do at 17.'