According to Jem in "To Kill a Mockingbird," what causes the difference in background?
In "To Kill a Mockingbird," Jem never specifically says what causes the difference in background. He does, however, discuss the different backgrounds in Maycomb, and these point to economic and racial distinctions. Jem says, "There's four kinds of folks in the world. There's the ordinary kind like us and the neighbors, there's the kind like the Cunninghams out in the woods, the kind like the Ewells down at the dump, and the Negroes."
In Maycomb, both economic status and race play a role in class. Jem tries to explain the Maycomb caste system by categorizing the four types of people found in Maycomb society. He then lists the types of people in order from the most to the least respectable and from poor to poorest. "Ordinary" people like themselves are at the top of the list. They live in normal houses in town and have descent jobs, but they are not wealthy.
Next come people like the Cunninghams, who are poor and live in the woods but who still work and have some sort of civility.
Following the Cunninghams are people like the Ewells who live by the dump, live off the government because they do not work, and live like animals.
Finally, and at the bottom of the list, are black people, who most people in Maycomb see as the least respectable type of people. Not only are they poor, but they are also African-American, and many people in Maycomb are racist.