How does Jem’s comment relate to the family history Scout provides over the next couple of pages? What is Harper Lee suggesting about the influence of the past on the events that take place in the novel?

This is actually a pretty detailed question for this short space. The main idea of Scout's historical perspective is to illustrate the point that people in the American South identify themselves by their historical roots. This is perhaps one reason why racism in whites is so ingrained and difficult to change. The old wounds from the Civil War have not yet healed and the hate of old Southern vagrants like Bob Ewell still resonates with most whites in the community.