What is the theme in The House of the Scorpion by Nancy Farmer?

One of the main themes in the novel, The House of the Scorpion, is that of humanity.... or how humanity is defined. Matt is a clone.... he is treated like an animal, and later treated like a prince. When El Patron gets sick, Matt is poisoned. At what point is Matt an individual? Can he be an individual? Is Matt a living, breathing being, who is capable of emotion.... or is he nothing more than housing for organ harvesting?