Suddenly realising how much the thesis of gravity falls is about not being defined by the issues of past generations

Soos realising that he doesn't need his absent father and the mystery shack is his new family. Pacifica refusing to be complicit in the crimes of her ancestors and making an effort to set things right. Dipper and Mabel resolving that they won't fall apart from each other the way that Stan and Ford did. Stan and Ford themselves reconciling with each other, despite everything that happened in their past.

All of them figure out that they can't let past mistakes, especially the mistakes of others, define them. You are the only one who gets to decide who you are.