What are the positive lessons that Jeannette Walls learned from her parents in The Glass Castle?
I think the most positive lessons Jeannette learns from her parents were not intentionally taught. Rather, they were perhaps the unsought consequences of living through childhood in "survival" mode with parents who didn't seem to know any better.
First, Jeannette and her siblings learned not to rely on anyone for anything, but instead to be as resourceful as possible on their own. They also learned not to get physically attached to anything that had sentimental or emotional value. Every time the family moved, the children were only allowed to take one important thing with them. For the most part, the children did not make any emotional attachments, and when they did, they learned to treasure something intangible inside them, rather than require something physical to fulful an emotional need.
The children learned how to stand up for themselves and each other. These kids were by no means crybabies, especially with a father who constantly reinforced the lesson that what doesn't kill you only makes you stronger.
We also know, at the end of the story, that no matter what her parents did or didn't do, somehow Jeannette managed to keep her sense of humor. Despite the debateable neglect and abuse of their children, throughout the story it is obvious that Jeannette believes she is loved. It is also obvious that there are as many fond memories of childhood as there are horrific ones. This says that both of her parents, for all their seeming worthlessness, were genuine and sincere in the raising of their children. They maintained a lighthearted approach, always, to poverty and hardship. They made things liveable and fun. Because of this, Jeannette and her brother and sister will always be able to look on the bright side, no matter what kind of difficulty finds them, and likely they will have the attitude that they can survive absolutely anything.
One lesson that Jeannette Walls learns from her parents is how to live in a way that is authentic. Her parents are unconventional, and at the beginning of the book, Jeannette (as an adult) catches sight of her mother rooting through a Dumpster to find items of value. However, when Jeannette asks her parents if they want anything, they respond that they don't need anything. While Jeannette finds herself feeling embarrassed about her parents, they are unapologetic and insist that they are living the way they want to live.
Jeannette Walls's parents also teach her not to become afraid of things. Even after she burns herself so badly that she is hospitalized as a young child, her mother tells her to "get right back in the saddle" (15). Her parents don't want her to be afraid of something like fire, and they encourage her to be bold rather than scared.
Finally, her parents teach her to get by without many material goods. When they are camping in the dessert, they don't have pillows, and Jeannette's father tells his children it's to teach them good posture. Their mother teaches them to wash themselves even with just a cup of water, and their mother ignores them when they are crying so they can learn to rely on themselves. As a result, Jeannette and her siblings are highly self-reliant.