What is the main conflict in Rich Man, Poor Man by Irwin Shaw?

Rich Man, Poor Man is the epic tale of one family; a tale that takes place from the turmoil of World War II to the beginning of Vietnam. There are three children in the Jordache family: Gretchen, the oldest, Rudolph, the responsible one, and Thomas, the troublemaker. The novel follows the lives of each member of the family, through happiness and turmoil, separation and reunions, and takes the reader on an emotional roller coaster that they will not soon forget.