What is the main conflict in Brothers and Keepers: A Memoir by John Edgar Wideman?

Brothers and Keepers by John Edgar Wideman focuses on John, the narrator, who is an educated black man, and his brother, Robby, who serves a life sentence in prison for armed robbery and murder. Through John's visits with Robby, the two discuss and examine their lives up to this point to understand how one brother ends up successful and the other ends up in prison.