Atticus's sister, Alexandra, is a gossip who is obsessed with the importance of the heritage of the people of Maycomb County. Scout discovers when Alexandra comes to live with them that her aunt is nearly equal to Miss Stephanie Crawford's own gossiping skills. Aunt Alexandra
... was an incurable gossip...
and she quickly became fast friends with Miss Stephanie. They
... had long visits... consisting mostly of Miss Stephanie shaking her head and saying, "Uh, uh, uh."
Alexandra judged everyone around her by their family upbringing, declaring that there were "Fine Folks," families with "streaks," and some--like the Finches--who were brought up through "gentle breeding."
I never understood her preoccupation with heredity.
Alexandra felt that the Finches were at the top of Maycomb's hereditary hierarchy, and some people, like Walter Cunningham Jr., were not fit to associate with Jem and Scout.
Aunt Alexandra is self-righteous, rude, and prejudiced, and she doesn't fit into the world of children at all. She seems to be the toughest on Scout for wearing pants and not a dress. At Christmas time in chapter nine, Scout argues that she can't do anything in a dress. Aunt Alexandra counters with the claim that she shouldn't be doing anything that requires pants. Aunt Alexandra also tells Scout she should be a ray of sunshine for her father, to which Scout replies that she can be a ray of sunshine in pants just as well. Aunt Alexandra demonstrates her self-righteous and rude personality by telling Scout the following:
". . . Aunty said that one had to behave like a sunbeam, that I was born good but had grown progressively worse every year. She hurt my feelings and set my teeth permanently on edge. . ." (81).
Needless to say, Scout isn't excited when Aunt Alexandra comes to live with them in chapter 13. Scout notices that her aunt mingles easily with the neighborhood gossips almost immediately. Scout says, "Aunt Alexandra fitted into the world of Maycomb like a hand into a glove, but never into the world of Jem and me" (131-132). That is to say that Scout's aunt is just as prejudiced and interested in gossip as rest of the town and not a progressive thinker like Scout and Jem are. And she's not a child, so she certainly doesn't understand childlike things.
Another time that Aunt Alexandra proves that she is prejudiced against other people who are not in her social class is when Scout says that she would like to invite Walter Cunningham over to play sometime. When Aunt Alexandra strictly declares that Scout will do no such thing, Scout asks why. The response she gets is the following:
"Because—he—is—trash, that's why you can't play with him. I'll not have you around him, picking up his habits and learning Lord-knows-what. You're enough of a problem to your father as it is" (225).
One might also add that Aunt Alexandra is manipulative as well as prejudiced because she tells Scout that she disappoints her father, but that's not what Atticus would say at all. He loves Scout for who she is, not for what she wears or with whom she associates as a child.