You're part Cornish? No way! I don't think I've ever met any other American who was, but I did hear tale once that the "Badger" nickname for Wisconsin had something to do with Cornish miners there. Who knows?
Do you know about Cornish nationalism? British politics was my field in grad school (when I became a Badger), and it turns out, much to everyone's surprise, there's a serious but very small Cornish nationalist movement, about reviving the language and even trying to bring back the Stannery Parliament from the Middle Ages as a devolved assembly, like the Welsh Assembly and the Scottish Parliament, for the Southwest (Cornwall & Devon). The party is called Mebyon Kernow, which means about the same thing as Plaid Cymru does on the other side of the water.
Definitely worth keeping an eye on, as they scored 1.7% of the vote in Cornwall in the last British parliamentary election.
All of which leads me to yet another Greyhawk question: Is Onnwall named after the fair land of (very few of) our ancestor's birth? I certainly treat it my game as being Cornish -- tin, pirates, etc.
http://en.wikipedia.org/wiki/Mebyon_Kernow
http://www.mebyonkernow.org/Public/Stories/89-1.shtml