How is social heritage introduced as a theme in this part of the book?

I I'm not sure if this is the point you are looking for but in December Charlie recounts the story of his paternal grandmother's experiences in an abusive relationship, and tells how the perpetrator was beat up by his grandmother's family and friends. Charlie's dad was never forgiven for leaving his family during those troubling times; as a result, Charlie's father has tried to compensate by giving small packages of money each time he visits.