Chris's parents, Billie and Walt, reveal throughout the novel that they are people with conventional moral and social views, who have never deeply questioned the norms and values of US society. This sets them apart from Chris, who confuses them.

Billie shows her conventional morality when she says.

“Chris didn’t understand how people could possibly be allowed to go hungry, especially in this country,” says Billie. “He would rave about that kind of thing for hours.”

Billie unconsciously diminishes Chris's concerns when she uses the term "rave" to describe his speech, characterizing it as lunatic, and when she says "that kind of thing" dismissively, as if social justice concerns must be handled with tongs.

Billie shows her conventional, risk-averse, middle-class American social values when she says:

“I just don’t understand why he had to take those kind of chances,” Billie protests through her tears. “I just don’t understand it at all.”

Like most Americans, Billie places a high premium on security and comfort. She doesn't comprehend that Chris felt most fully alive when taking risks and challenging himself to get out of his comfort zone. She didn't understand that risks were part of his spiritual quest, a way to expand his soul and gain greater wisdom.

When Walt describes Chris's quirks with racquetball, he shows that he doesn't understand how Chris would value playing for its own sake more highly than becoming more competitive so as to be a winner:

He was very, very quick and had a lot of power; but when I suggested he work on the gaps in his game, he refused to listen.

Walt and Billie, Chris McCandless's parents, did not understand their son very well and placed far greater value on material goods than he did. They grew up poor and wanted the kind of material stability that comes from having a steady job in a reliable field, something that Chris rejected.

When Walt later reflected on seeing Chris at his college graduation, he said, "We misread him." Chris's parents were unaware that he was going to dedicate all the money they gave him at graduation to OXFAM. When Walt found out that Chris had given away his money, he said, "The hitchhiking ticket just didn't make any sense. He loved that Datsun so much it was mind-boggling to me that he would ever abandon it and travel on foot." Even after the fact, Walt did not understand Chris's desire for total freedom, and Walt later said of his son, after his son's death, "I really liked Chris's company though he frustrated us so often." 

It was apparent that Walt and Billie did not understand Chris's desire for independence. When Chris failed a physics class because he refused to follow the teacher's directions, Walt went to speak with the teacher. He recalled, "After talking with the guy, I came home and told Chris he got the grade he deserved." Walt was not in favor of Chris's breaking the teacher's rules just because he found them pointless. Billie said of her son's adventures, "I just don't understand why he had to take those kinds of chances." Both parents wanted their son to live a kind of sedate and safe life, which Chris completely rejected, to his parents' bafflement. 

There is a real tragedy in the fact that Chris McCandless and his parents were unable to connect in a way which may have saved them all from heartbreak. His father Walt is able to articulate why they became so distant, telling us in chapter 3-

We misread him

The resentment Chris held for his parents unconventional union was deep seated, and never articulated to them. It is sad that he could share his feelings with his sister Carine, but not with his parents. The letter he sends to her, detailing his plan to cut himself off from his family, reveals a visceral bitterness –

I’m going to completely knock them out of my life. I’m going to divorce them as my parents once and for all and never speak to either of those idiots again as long as I live. I’ll be through with them once and for all, forever.

Walt and Billie cared deeply for their son. Walt tried to talk to Chris after he nearly died having been lost in the Mojave Desert. He was aware of his son’s inability to accept authority, but wanted to protect him anyway-

I’d learnt by then that a direct approach – ‘By God, you’d better not try a stunt like that again!’- didn’t work with Chris. Instead, I tried to explain that we didn’t object to his travels; we just wanted him to be a little more careful and to keep us better informed of his whereabouts.

His words had little impact other than to irritate Chris.

In Into the Wild, what are some quotes that represent characteristics of Chris's parents?

Chris’s mother says half way into the book, “I just don’t understand why  he had to take those kind of chances. … I just don’t understand it at all” (132). Krakauer’s placement of the grieving mother’s statement here, after providing reasons others have given and various accounts of Chris’s adventure, serves to show that no one yet has been able to give information that would assuage this mother’s deep sorrow.  She wants some closure from her son’s death but has none, and does not find any until she visits the site of his death at the end of the story. Walt, Chris’s father, reveals much about himself and his relationship to his son when he tells Krakauer an anecdote about Chris’s performance at school when Chris received an F because he did not turn in his lab reports in a particular, required format. Concerned, Walt called the teacher, and “After talking with the guy, [he] came home and told Chris he got the grade he deserved” (109). This comment indicates that Walt, like the teacher, values following the rules, and it is this that Chris resented so much; it is one reason he disliked his father so intensely and thought him devoid of a real moral compass. But it also indicates that his father provided a structured and moral environment for his son as a child, even if Chris ended up rejecting that.