it's interesting you mention east coast: I'm thinking that's New York and the old racial divisions between italian, irish, jewish and other immigrants from the early 20th century. plenty of stereotypes which New Yorkers seem to have been able to overcome mostly. Perhaps you're right and the way they have done that is by laughing about it . . . . there's a lot to be said for humour.
don't worry about france and italy it would take too long to explain. Watch some of their films if you can.