Carine McCandless waited 22 years to write the story of what pushed her brother Chris to disappear into the Alaskan wilderness on an ill-fated adventure that was later chronicled in Jon Krakauer’s best-selling book Into the Wild and in Sean Penn‘s 2007 movie of the same name.
“I just felt it was time,” Carine, 43, tells PEOPLE. “I think it’s important for people to have the facts.”
Those facts, painfully detailed in her new book, The Wild Truth, out Tuesday, reveal that it wasn’t just her brother’s love of nature and adventure that drove him, but his longing to break free from his violent, manipulative and verbally abusive parents.
“I don’t blame my parents for his death,” says Carine, “but I hold them accountable for his disappearance.”
The 24-year-old McCandless made headlines in August 1992 when a moose hunter near Fairbanks, Alaska, discovered his withered body in a sleeping bag inside an old bus used by locals as a wilderness shelter. He had arrived over three months earlier, intending to hunt wild game and forage for food from local plants, but by the time he died he weighed only 66 lbs.
Carine’s book details the siblings’ upper-middle-class childhood in the suburbs of Washington, D.C. On the surface, life was idyllic. But behind closed doors, their father, Walt, a successful aerospace engineer, and their beautiful mother, Billie, would drink heavily, writes Carine. She also details how her father would often hit and choke his wife, and – in between belittling his family – occasionally physically assault his kids.
Even more painful, for part of Chris’s and Carine’s childhood Walt had another family – including six other children – and split his time between them.
The two siblings were extremely close, but McCandless, in an effort to escape his dysfunctional home life, disappeared after his graduation from Emory University in May 1990 and embarked on a two-and-a-half-year odyssey of hitchhiking and backpacking around the country that ultimately ended in his death.
“He had a love of adventure, but that wasn’t all that drove him,” says Carine. “Our parents pushed him to a level of extremity where he peered over the edge just enough that he lost his footing.”
In a statement released to the media earlier this month, Carine’s parents dismissed her book, calling it “fictionalized writing [that] has absolutely nothing to do with our beloved son, Chris, his journey or his character. This whole unfortunate event in Chris’s life 22 years ago is about Chris and his dreams.”
Carine, who hasn’t seen her parents “in several years,” tells PEOPLE that she didn’t write her book to hurt them.
“It might come across as mean, but that was never my intent,” she explains. “I have a lot of sadness for them, but I just wanted to tell the truth. I know that’s what Chris would have wanted also.”