I know at least one of these people isn't a junior (although oddly, his younger brother is).
Well, how many people slap Chuck on their kid's birth certificate as opposed to Charles? They're both one syllable C names. But one's more formal than the other. Americans like their sons to have formal full names more so than other Anglo countries.
My university has a student directory, so looking at it there's 26 Johns who have put in that they prefer Jack. One is an IV, but if the rest are a Jr./III/IV, they don't have it listed. There's also two Jonathans who prefer Jack, which shows how solid the nickname association is in Massachusetts.
This message was edited 9/7/2019, 3:09 PM