How do Naomi and her brother, Stephen, differ in character, and how do they view their Japanese heritage?

In Joy Kogawa's novel Obasan, Naomi and her brother, Stephen, have very different relationships with their Japanese heritage. The novel is about the internment of citizens of Japanese descent in Canada during World War II, which Naomi, now an adult, remembers happening during her childhood.
Although Naomi, now a schoolteacher without a family of her own, struggles to forget the horrors of her past and she wonders about the ways traditional Japanese gender roles might have hurt her and other Japanese women, Naomi has more of a connection to her family. She feels a strong connection to Obasan, her aunt, and her uncle, who raised her, and her visit with Obasan brings up her memories of what it was like to grow up as a Japanese Canadian girl when she did. In the end, she feels a connection to her mother.
Stephen also tries to forget his past, but he does so far more than Naomi; he represses everything about his Japanese heritage. He is embarrassed by his family and anything that might be considered "too Japanese," and he has willfully tried to forget anything about the language and culture. He is outwardly more successful than Naomi—he has a functioning relationship and successful career as a musician—but he is very unhappy due to his complete repression of the events of his past and everything about his heritage and family.
On the surface, with regard to traditional Western expectations, Stephen is more successful than Naomi, but it is Naomi who faces her demons and connects to her culture more than Stephen ever does.