Paul is an innocent young boy who tries desperately to help his family. His mother's manner (her outward behavior) towards the children is "gentle and anxious." So, it appears that she loves them, but inside, she really has no love for them. Paul's parents do not make enough money and Paul's mother attributes this to bad luck or lack of luck. She says luck is what causes a family to have money. She says this instead of pointing to hard work as a means to making money.
Paul takes it upon himself to obtain the luck the family needs. He doesn't realize it, but he essentially becomes like a parent to his parents. In picking winners of the races, he is the one bringing in the money. His mother spends it frivolously, proving how she is the immature, irresponsible one while Paul is the responsible breadwinner of the family. Their roles have reversed. His mother and father do not know of this role reversal until it is too late. Plus, with the money coming in, they don't want to change their newfound luck. When Hester, Paul's mother, spends the money and requires more, Paul pushes himself even more. Some critics also claim that Paul is acting out a sexual desire. As he is on the verge of adolescence, he conflates the ideas of sexual desire and the desire for luck/money as rites of passage en route to adulthood. In the end, Paul sacrifices himself for the sake of his family.