Infiltrating the Airship
Smith is evidently a member of the Toppat Clan that is never seen. Henry Stickmin is mistaken for him in the Disguise option and forced to abort the mission due to "Smith's wife' being pregnant". From this information, we know he has a wife and child. We also know he looks a lot like Henry. You can see him telling Wilson they had to get out of the building.
Fleeing the Complex
Two guards at the outer docks of see Henry Stickmin escaping on a dinghy, but mistake him for Smith saying, "Someone just leave?" "I think it was Smith..." "Oh yeah probably just off to see his family". This is a reference to Infiltrating the Airship where Smith is likely now to be a father. This also means Smith is possibly undercover in The Wall like another Toppat member, or perhaps is said Toppat agent.