Oshia is Nnu Ego's second-born son but the first to survive into adulthood. He is clever and does well in school, so well that he's accepted at prestigious (and expensive) high schools. Though his family makes many sacrifices so he can go to school where he wants, he fails to appreciate it, and takes for granted that he can get what he wants.
His selfishness is borne from two things: the fact that he's the first-born son, which grants him privileges and honor from the first day he is born; and his association with wealthy students at his high school, where he learns to expect more from life than what has been given to him.
Oshia's family expects him to help out when he graduates, by taking a job and helping to pay for the younger children's education. It is expected that he will repay his parents and siblings for everything they have done to help him succeed. However, Oshia proves selfish and leaves for America to get a university education instead. He doesn't even help his family when Nnaife gets in trouble with the law. That Oshia fails to help his family is particularly devastating to his father. Not only does Nnaife curse his son and effectively disown him, but also he takes it a step further and curses Nnu Ego for giving him such selfish and unhelpful children. Nnu Ego refuses to disown Oshia, but it is clear that the young man's behavior is a person blow to her as well.
Once he leaves for the United States, Oshia stays away until his mother dies. Only then does he return, in order to throw her an expensive funeral. Though he neglects his mother during his life, he honors her in death.