Remember that we're talking about a generation ship - after a very short fraction of the mission time, everyone will have been born on the ship.

(Does the ship have a class system? Is the ship structured as a commune? Do people "own" bits of it, or is it more of a feudal tenure system? Can you maintain a multigenerational society on a military command structure when there is no external enemy other than the vastness of space? Would you want to?)