What is the main conflict in A Vietcong Memoir: An Inside Account of the Vietnam War and Its Aftermath by Truong Nhu Tang?

The story begins with Truong Nhu Tang's description of his childhood, a situation he calls the "family cocoon." In this protective life, it is decided by Tang's father that Tang is to become a pharmacist. His older brother was told by their father to become a doctor, and the plan is for the two brothers to go into practice together, a practice that will be exemplary and profitable for both. Of Tang's younger four brothers, one is to be a banker, who will finance the engineering endeavors of the remaining three, all destined by their father to become engineers.