Amir, to win his fathers approval allows for the rape of Hassan to occur and becomes an insomniac as a result. Amir, believing Hassan is the price (he) (has) to pay, allows him to be raped, causing him to carry an enormous amount of guilt and shame with him, until he seeks redemption, forcing him to become an insomniac, as he is no longer able to be at peace with himself. By moving to America, Amir believes he can bury (his) memories and forget the traumatic events of the winter of 1975.
However, the amount of guilt Amir is carrying with him for not correcting his wrongdoings is what forces him to eventually return to Kabul and seek redemption. Amir, who is a coward when a child, remains so until he is forced to sacrifice himself for Hassan, by facing Assef in order to rescue Sohrab, and ultimately gain redemption. Baba leads a tormented life as he is never able to overcome his guilt of not acknowledging Hassan as his son. Baba, because of his childhood, is never able to bring himself to admit that Hassan is own son and as a result is a tortured soul.
Throughout his childhood, Baba growing up with Ali, becomes aware of the social inequalities between them, and this affects his inability to claim Hassan as his own son. Baba grows up with a sense of superiority at being a Pashtun, which is the biggest reason holding him back from owning up to his actions. As it is a shameful situation, Baba does much charitable work in order to achieve redemption, but nothing he does is able to overcome his guilt and shame at not giving Hassan the life he deserves, as a Pashtun.
Assef, who has horrific thoughts and views as a child grows to be a member of the Taliban. Throughout his childhood, Assef bullies many of the neighbourhood children, being viewed as a sociopath, controlling them through his stainless steel brass knuckles, and keeping them at a fearful distance from himself. Assef has a shocking vision of eradicating the Hazaras, and being a member of the Taliban years later, this is put into practice, when all the Hazaras in Mazar-i-Sharif are massacred.
Assef, being a bully in childhood, obtains a sense of power through controlling those around him through a sense of fear, grows to be a member of the Taliban, who also control the country through the sense of fear they instill in their citizens of Afghanistan. Through Amir, who becomes an insomniac at his guilt and shame of not preventing a horrific crime, Baba, who is a tortured soul at not being able to admit to his actions, and Assef who grows up to be a member of the Taliban from being a bully, Khaled Hosseinis The Kite Runner demonstrates how we will grow up to be products of who we are when we are young.