Where in To Kill a Mockingbird does Atticus admit to shortcomings, saying that he is trying his best as a parent?
After Aunt Alexandra, a Southern woman who is very concerned with class and social distinctions, arrives at the Finch home in Chapter 13, she confers in private with her brother Atticus about the proper rearing of his children. For, one day she calls Scout to greet some ladies who have come over, but when Scout appears in her overalls that are covered with sand, "she regretted her request." Then, when Scout does not politely say "hello," but instead asks who they are and remarks about Lily Brooke, "She our cousin? I didn't know that," Aunt Alexandra is mortified, conveying an apology to Cousin Lily and disapproval to Scout.
That evening Atticus knocks on Jem's bedroom door where Scout also is; fidgeting, he tells the children in the most serious of tones,
"Your aunt has asked me to try and impress upon you and Jean Louise that you are not from run-of-the-mill people, that you are the product of several generations' gentle breeding---"
Having upset Scout, Atticus tells her to "Forget it." Then, he asks the children if he is getting more like Cousin Joshua [an eccentric relative].
In Chapter 14, Aunt Alexandra also disapproves of Calpurnia's influence upon the children because she does not think that the black maid should be the one to take the place of a mother. However, Atticus defends this position, saying that Calpurnia has
"never let them get away with anything, she's never indulged them...."
But, again, Alexandra points to Atticus's failure to raise Jean-Louise as a proper young lady.