Pudd’nhead by Wilson

Percy Driscoll names his child Tom. However, after Roxy switches the babies, Twain refers to the young usurper (who is really a slave) as "Tom." This false heir, due to his overindulgent upbringing, grows to be spoiled and cruel, particularly to slaves and other blacks. He picks up the habits of drinking and gambling while away at Yale. His gambling gets him into deep debt, and he resorts to robbing the citizens of Dawson's Landing to meet his obligations.Roxy's son. Roxy switches her child with her master's child, so Twain refers to the true heir as "Chambers." Chambers is raised as a slave, and grows up to be meek and docile, but a strong fighter and good swimmer. Tom forces Chambers to serve as his bodyguard. Chambers is the primary target of Tom's cruelty, who is jealous of the slave's natural physical abilities. After Pudd'nhead Wilson reveals that Chambers is the real Tom Driscoll, Chambers suddenly finds himself free, rich, and white. However, because of his slave upbringing, he does not feel comfortable in the white man's world. I think one of the running themes here is the enormity that the environment has on the child.