Given the age of Chris and the approximate ages of those he encountered, do you think that krakauer is overstating the effects of a strained relationship with his parents?

I don't think Krakauer is overstating because of the devastating effect that Chris's actions had on his family. Chris tells his sister, Carine, that he intends to soon cut off all relations with his parents, for good, disgusted by their attempts to control him and what he sees as their immoral lifestyle. Note, he loves his sister.

We also start to see some of the reasons for McCandless’s estrangement from his family. Although in some ways it seems like his choice to cut himself off from his family is an important part of his plan to have true freedom, it becomes clear in this section that in some ways it is intended specifically to punish them. He tells Carine soon before he disappears that he intends to cut his parents out of his life completely, because he resents their values, and their attempts to impose those values on him.

It is also interesting to see in this section how McCandless’s expectations for his parents are so much higher than for other people in his life. He holds himself to these same standards, always living by the philosophies he espouses, and the standards he holds others to, but he is forgiving of many sins from his friends, including alcoholism and mistreatment of women. Yet even the offer to buy him a car as a graduation gift, coming from his parents, is enough to make him completely disgusted with them, even though, with Carine for example, he does not hold her materialism against her.