Wally Mack's father is not a man to be trifled with. He is overly protective of his family. He's taught basic survival skills to his children but isn't overly fond of showing emotion. Should Overseer Almodovar ever become incapacitated, Allen has vowed to take over the running of Vault 101.
During the quest Escape!, it is impossible to enter the room where the Macks live (except for use of console commands). Viewing Vault 101 in the G.E.C.K reveals that Mack's 'room' is just a short stretch of corridor with no entrances.
One of his combat lines include "The Overseer will hear about this!", even after he becomes the Overseer.