What does, "Aunty said no, that's where we got our small hands and feet" mean in Chapter 13 of To Kill a Mockingbird?
Prior to this, Atticus and Aunt Alexandra are speaking about family reputations, and Atticus proposes that the Finch family could be considered to have an "incestuous streak". I do not understand the connection between the quote from above and the "incestuous streak" Atticus is talking about.
This is a rare glimpse into Atticus's sense of humor in To Kill a Mockingbird. Aunt Alexandra has been lecturing the children on her belief in Family Streaks--
Everybody in Maycomb, it seemed, had a Streak: A Drinking Streak, a Gambling Streak, a Mean Streak, a Funny Streak.
Alexandra, of course, does not believe the Finch family has any such streaks, since she believes them above such indiscretions. But Atticus points out that his own generation of Finches--including himself, Alexandra and brother Jack--are
"... practically the first... not to marry its cousins. Would you say the Finches have an Incestuous Streak?"
Aunty said no, that's where we got our small hands and feet.
This conversation refers to the old practice of families (often wealthy) to marry their first cousins in order to keep the money within the family (instead of distributing the wealth to outsiders). Marrying first cousins is illegal in many (if not most or all states) because mental retardation and physical deformities are much more common among the children produced by first cousins. Since, apparently, previous members of the Finch family had married their first cousins, Atticus jokingly suggested that the Finches may have an Incestuous Streak. Alexandra, in reply, denied the Streak, but admitted that the past generations' breeding among first cousins were responsible for the family's own "deformities"--"small hands and feet."