situational irony in literature is when children take on traditional adult roles.  This is ironic, of course, because young children are expected to be dependent on the care, experience and wisdom of the adults in their lives.

This is the ironic premise that The Glass Castle is built on.  The main character, Jeanette, and her 3 siblings, are subjected to what should be considered abuse and neglect by their parents over and over again as young children.  Most often they are taking care of their poor and crazy parents, making excuses for the lack of parenting, and watching out for one another.  However, throughout the kids' lives, they never question whether this is normal.  Likely they know they are different from other children - but never do they consider their lives as bad.  In fact (further irony) the story is lightheartedly tragic as they celebrate what would otherwise be considered child abuse as "adventures."  Also, throughout the story, all the children love each other and their parents more than anything in the world.  I think too that through such an unconventional upbringing, the children eventually consider themselves better as a result.

If you keep this in mind as the foundation for irony in the novel, you can find specific examples to support it in absolutely every chapter.

Irony exists in Jeanette Walls's explanation that her parents were seeking to raise their children properly, in ways that were much better than the upbringings they experienced at the hands of their own parents. Ironically, though Rex and Rosemary feel that their own parents were unskilled at parenting, they show very little skill themselves. Few of their parental decisions indicate a knowledge of important child-specific concerns like health, safety, hygiene, and other basic notions of family life.

Specifically, Jeanette's child self was in charge of providing financial and emotional support to her siblings—two roles typically held by adult parents. As well, Rex and Rosemary are unable to take Erma's attempted molestation of Brian seriously, while Lori, also a child, realizes the seriousness of Erma's offense and the potential damage she could have inflicted on her brother.

One of the ironies of Jeannette Walls's story is that she winds up living on Park Avenue, while her mother is rooting through a Dumpster in Manhattan. While Jeannette is surrounded by Persian rugs and wears pearls, her parents are rooting through garbage looking for goods. The irony is that her life has turned out very differently than that of her parents, and the contrast between her life and theirs is striking.

Another irony is that her parents seem to be happy with their life of poverty. They live without excuses or explanations, and they are content with what they have and the life they have chosen. However, Jeannette, while living what many would consider a life of relative ease on Park Avenue, is beset with worries--about her parents on one hand and about what other people think of her on the other.

The book is filled with ironies about Jeannette's childhood. For example, when she burns herself because her parents basically neglect to watch her as a young child, she is taken to the hospital, where she receives attentive care. Her father asks if the hospital staff is taking good care of her, which is incredibly ironic, because it was her parents' neglect that landed her in the hospital in the first place. 

Probably the strongest example of irony is one we learn as the book ends.  Jeannette's mother Rosemary had considerable wealth that could have fed and clothed her children and provided a home for them, but she felt she needed to hold on to this property.  This irony is foreshadowed by the children's discovery of a diamond ring.  When they learn that it is a real diamond, they want to sell it, but Rosemary says that she "should have nice things." 

The title The Glass Castle highlights the irony of the castle Jeannette's father Rex promises the children.  Although he is knowledgeable scientifically, it becomes clear to us that the glass castle will never truly exist.  It is ironic that he describes it as glass because glass is fragile and unsustainable, like the Walls family itself.  It is also ironic in that it suggests a fairy tale existence in contrast to the squalor in which the family actually lives. 

We can see irony in the loyalty and love the children have toward their parents despite what many of us would consider neglect and even abuse.  It is this mix of love and dysfunction that makes this a conflicted and powerful book.  

There is even irony in author Jeannette Walls' fear of what people would think of her after she published the book. In an interview she claims that she was fearful of people's reactions.  This is ironic in light of the resiliency she shows in the book itself, but it also reflects the mix of vulnerability and resiliency (possibly an ironic mix) that drives the narrative of this book.

The most obvious example of irony is that the father may dream of glass castles and create magical stories about them, but they actually live condiitons of the extreme opposite of castles. At two different points in the story they live in an abandoned boxcar and later they live in a broken down shack that doesn't have a solid roof, running water or proper heating. The children live in abject poverty. Another aspect of the irony of this is that glass castles aren't real and suggest fragility, which is a clear description of how fragile and vulnerable the children are in the conditions in which the parents have them live.

Another example of irony is that Rosemary, the mother, actually grew up with great stability and a great sense of economic security, yet she allows her husband to make grave decisions for the family and she goes along with them even with the risks to her children's welfare. Rosemary has a teaching degree, but rarely uses it to better the family's life even when she has the opportunity to do so. She seems rather selfish and at times self-absorbed; she behaves in a very contrary manner to the way she was raised.

Other smaller examples of irony: the children have nothing to eat, and the father drinks rather than feed his family. Jeannette has every reason to hate her parents for the way she was raised, yet the novel speaks to the love she will always have for them. The youngest sister, Maureen probably had it the easiest as a child, and yet she is the one who has had the hardest time making herself into a successful adult.