Atticus's sister, Alexandra, is a fanatic about heritage and family history, and she believes her Finch family ancestors are without peers in Maycomb. Atticus, however, doesn't agree. Atticus has already told the children about Joshua S. St. Clair, Alexandra's most revered family member and an author of a small book of poetry. In truth, Joshua
"... went round the bend at the University... tried to shoot the president... Atticus said it cost the family five hundred dollars to get him out of that one..." (Chapter 13)
This revelation angered Alexandra, and she chewed out Atticus, who "soberly" came into the children's bedroom to explain all about his sister's belief in "gentle breeding." But Atticus didn't believe in it himself, and after he brought Scout to tears, he returned to apologize. In answer to Scout's question, he told her that
"I don't want you to remember it. Forget it." (Chapter 13)
He left the room in a most un-Atticus-like manner.
His eyebrows were raised, his glasses had slipped. "Get more like Cousin Joshua every day, don't I?" (Chapter 13)
Atticus reveals that he is humble, apologetic when appropriate, and that he has a self-deprecating sense of humor. But most importantly, he understands that the makeup of a man is not based entirely on his past heritage, but with the individual.