One of the themes in "The Shawl" is trauma and how traumatic experiences can be transferred and translated, in family life, from one generation to the next. The narrator relates a story about his father. His father's mother fell in love with another man. Eventually, she left and took her daughter with her. As the wagon left, the boy (father) chased the wagon until he could not run anymore. This was such a traumatic experience that it changed him:
He watched the back of the wagon and the tiny figures of his mother and sister disappear, and something failed in him. Something broke. At that moment he truly did not care if he was alive or dead.
What made this worse was that the boy discovered that his sister had later been killed by wolves. The boy kept the shawl his entire life. Therefore, he held onto the memory but also held on to the pain, to that trauma.
The boy became a husband and father himself, father to the narrator of this story. When the now father began to drink, the narrator and his siblings began to view their father as someone to be avoided. The narrator fights his father when he feels strong enough to do so. This marks a change in his father's behavior. Finally, the narrator convinces the father that he should burn the shawl. This shows that the father might have finally accepted the fact that it would be wise to move beyond, or forgive, the trauma of his childhood. The narrator also suggests that his father's sister might have sacrificed herself (rather than the mother having pushed her to the wolves).
Considering that the sister might have sacrificed herself, the narrator suggests a reconsideration of the past, a rewriting of the past. There is the sense that this is a way to make a tragedy at least somewhat positive (the sister's sacrifice) but it also speaks to a more general, unstated theme in the story which is about the plight of American Indians and their struggles to remember the trauma of their past (relative to European colonialism and the conflicts therein) but also to move past it and establish a better future.