What is the theme in The Inheritance of Loss by Kiran Desai?

A major theme throughout the book is the class and the caste system. Indians have a very rigid class system, where it is perfectly legal for them to treat other members of society as their slaves, as the judge treated the cook. Every character is exposed to this class divide, and Sai and Gyan are the only ones that cross that line, harboring an innocent and free romance, which is later killed by their social differences.