The overriding themes in Khaled Hosseini's novel The Kite Runner can be found in virtually every chapter of the book.
The primary theme is one of self-discovery by the narrator, Amir. The story chronicles Amir's life from birth until many years into his adulthood. Over and over again, whenever he is faced with a difficult choice, Amir makes the most expedient and comfortable decision for him. He has little regard for loyalty, friendship, or family. He lives his life as a betrayer of the worst kind, and his eventual realization of this awful fact nearly breaks him. By the end of the novel, he is striving to atone for the grievous wrongs he committed.
A second theme found in The Kite Runner is the role of heritage in shaping one's life. Amir's father is a proud Afghani who is forced to flee to America when the Taliban arrives in his country. Nevertheless he remains loyal to the traditions and practices of his native country until the day he dies. For Amir, the move to America offers him the opportunity to forget his past; however, he does not abandon his heritage and, in fact, finds strength in its customs and traditions as he tries to rectify his past mistakes.
A third theme which is clear in this novel is the relationship between fathers and their sons. Amir's mother dies in childbirth, and he grows up loving his rather distant and demanding father--who Amir discovers later hid a monumental secret from him. Amir's half-brother, Hassan, also grow up without a mother; she leaves to pursue her own selfish desires as soon as she sees that Hassan is deformed (he has a harelip). The importance each boy attaches to their fathers (and father-figures) is central to the jealousy which prompts Amir to do awful things to hurt Hassan. In the end, it is another father-son relationship (Amir and Hassan's orphaned son) which may redeem Amir.
The link below lists several other themes for this novel. Because these themes are obvious and pervasive in the story, each chapter contains events which contribute to them.