Hiro would have chalked it all up to class differences, except that her parents lived in a house in Mexicali with a dirt floor, and his father made more money than many college professors. But the class idea still held sway in his mind, because class is more than income—it has to do with knowing where you stand in a web of social relationships. (7.31)
Social class and family are closely related, with factors like income and location affecting how many kids a family might have, how they educate them, and so on. Hiro may feel baffled by his family's lack of defined identity (thanks, Army), but then again, not having a fixed family identity gave Hiro the freedom to become whoever he wanted to be. In this case, a master hacker and rockin' swordsman.