What kind of Americans? Say they are a Sioux-Polish American from Chicago and an Irish-Mexican-Mongolian American from Houston, then yeah, why not call the kid Chinese. My mate was born on holiday in Australia and only lived there for a week, yet had to go through naturalisation over 20 years later to become the same nationality as his parents, as they had forgot to fill out the forms at the time.

So presumably Tesla was a Croatian-Serb, or possibly a Serb-Croatian, and whether or not those two groups get along doesn't really affect that definition. I mean, I fully understand that it is a touchy subject, but I don't really think that it affects long dead physicists very much.