In-Universe, Boogie is Francis' brother-in-law
- This would explain why Francis' sister is played by Boogie's Wife: they're the same character! Francis doesn't acknowledge this because he's uncomfortable with the idea that his sister got married while he remained a bachelor Manchild.
- Jossed: Francis' sister is dating David, a different character entirely, at the time in which Boogie is married to his current wife.
Francis In-Universe is just a Split-Personality Takeover
Francis is no different than The Mask, The Nutty Professor, and other characters from media who have split personalities. The only difference is in universe Francis didn't come from wearing a mask or any science experiment gone wrong he manifested overtime.