What is the theme in Pigs in Heaven by Barbara Kingsolver?

One of the main thematic concerns in the novel is the issue of justice and injustice. At the heart of the story is the following question: should an adopted child be taken away from a mother who provided her with the only comfort and love she has ever known, so that the child can gain a sense of her cultural identity? In response, both sides have valid and relevant points; as a result, it is difficult to come up with a definitive answer.