I watch MitM on 5*, and the EPG on my TV regularly refers to the family as "The Wilkersons"!
At Marlin Academy the lack of a surname seems wierd, since all other Cadets use surnames to address each other, but call Francis: "Francis". In the episode with the "Brothers of the Apocalypse", they call Ken Finley "Finley" in their chant, but Francis is called "Francis". His name tag in later episodes syas Francis as opposed to his surname as well. It just seems wierd that everyone treats Francis differently.