Jon Krakauer, the author of Into the Wild, provides readers with only a few clues and suggestions as to the true nature of the relationship between Chris and his father; this omission was deliberate, according to Chris's sister Carine McCandless. Because the violence and abuse that characterizes the father-son relationship was only hinted at in the book, some readers feel that Chris acted selfishly or that he pursued a foolish dream without a regard for safety, suggesting that he was mentally unstable. According to a memoir written by Chris's sister and published nearly twenty years after Krakauer's book, titled The Wild Truth, both their father and their mother were at times abusive toward their children, and these early life experiences most certainly motivated Chris to make the decisions that eventually led to his death.

According to Carine, living with abusive parents inspired Chris to take risks and to seek out extreme ways to express himself. Because Chris had always had a love for adventure and for nature, it makes sense that he would see an opportunity to prove himself that blended with these personal interests. From the point of view of Chris's sister, Chris's need to wander (documented in Into the Wild) was directly related to the difficult relationship he had with his father and his mother. Chris's urgent need to escape his parents and to disappear reflects the depth of the trauma he experienced at the hands of his parents, and thanks to Carine's account, the truth about Chris and his parents is now available to all readers.

Chris McCandless's relationship with his father, Walt, was the strained relationship of two people who are innately alike yet reject one another's principles. That said, part of Chris's desire to reject his stereotypical life and go out on his own seems to be uniquely him: his sister, Carine, stated: "Even when we were little...he was very to himself."

From a young age, Chris witnessed the grueling work his father and mother put into their consulting firm, and Krakauer notes, "it was a stressful experience," first due to the difficulties of earning enough to support Walt's children from both his first and second marriages and, second, due to Chris's parents' extraordinarily stubborn personalities. His parents were able to stay afloat and then make enough money to afford modest luxuries, which embarrassed Chris. 

In my opinion, Chris greatly resented the grueling work and arguments that eventually afforded his family these luxuries, and thus he was someone driven by his parents, particularly his father, to take to the wilderness. However, I also think that Chris's "overdeveloped social conscience" was a trait with him since birth, and also a contributing factor that led him to take his eventual trip to Alaska.

Chris had a troubled and very angry relationship with his father. This relationship--or Chris's rejection of it-- was centrally important to motivating Chris's behavior in the few years he had between graduating from college and dying in Alaska. 

Chris forcefully rejected his father's materialism, telling his sister that he didn't want to be "bought." In response to what he believed were his father's attempts to smooth over difficulties with money, Chris rejected money. He gave an inheritance he received to Oxfam, then later abandoned his car and burned his cash. He deliberately lived on the margins of society, working at different times at a ranch or at a MacDonald's. When he hit the road after college, he was so determined to be out from under his father's control that he didn't let anyone in his family know his whereabouts. This, as we know, had fatal consequences: when Chris got into serious trouble, nobody knew where or how to find him.

Chris also despised his father for having a second family that Chris knew nothing about growing up, leading him to believe his whole childhood had been a sham. Chris's determination to be different from his father drove him to read authors who advocated a simple life, such as Tolstoy and Thoreau, to live alone for long periods and to pursue his counter-cultural path. 

Considering the above post, making "truth" the focus of your essay would be a good way to go.  Use the essay to develop the many ways that Chris did not have "truth" at home -  the double life, the materialism, the "phony" socialite life - and then compare those things to the "truths" he is looking for in the world and in wilderness. 

Chris McCandless' relationship with his father was strained at best.  Chris was an opinionated, determined, and stubborn young man with high ideals and little room for compromise.  His father is a hardworking man with high standards who shared his son's inabilty to compromise.  Chris was always critical of his parents and their lifestyle, but that criticsm turned to outright anger when Chris learned that his father had lived a double life with another family for a time.  Chris saw his father as a liar and a hypocrit and he was never able to forgive his father.  A recurrent theme in Chris' journal was a search for "truth", and he linked that search to the lack of truth he perceived in his family life.  After graduating from college Chris felt the need to flee from his family and their expectations in order to seek the truth that he felt he had never experienced.