Some people might be bitter if they grew up with parents like Rex and Rose Mary Walls. Jeannette starved on a regular basis. She had to raise her siblings because her parents didn't. Her dad once used her to sexually entice a gambling buddy when she was a teenager. Yeah, all that might make a person angry. Not building the Glass Castle is the least of Jeannette's parents' offenses.
But Jeannette forgives the 'rents. She closes the book with positive stories about each parent to leave readers not feeling angry with them. Jeannette has a final conversation with her dad before he skedaddles to the great beyond, and when he asks her, as he often does, "Have I ever let you down?" (4.12.41), she gives him the most honest response she can: she doesn't answer.
Mom doesn't quite get off as easily. Jeannette learns that Mom held on to land worth one million dollars for most of her life, which was the Get Out of Jail Free card the family desperately needed. But Mom never played it. Maybe because Mom was still alive when Jeannette wrote the book, Jeannette doesn't express how extremely angry she must have been at this news. In fact, Jeannette doesn't tell us how she feels at all—and that silence says volumes.
In the end, we see the Walls family reunite at Thanksgiving, always a heart-warming time. When Jeannette's step-daughter says that Jeannette's mom "laughs just like you do" (5.1.15), Jeannette realizes that no matter how far she runs and how much she changes, she'll always be a little bit like her mom.
The book ends with a heartwarming toast. Mom says, "Life with your father was never boring" (5.1.25), and the family shares funny stories about Dad. Probably not the stories where he almost killed them, or the stories about how he defended his own mother after she sexually assaulted his son. Oh, well. The family focuses on the positive. We guess that's how they managed to survive this long, after all.