From NPR:
But questioning where someone is from can be loaded for Asian-Americans, said Jennifer Lee, a sociology professor at the University of California, Irvine who studies race, immigration and culture. … ”It's this persistent perception that Asian Americans are not American, that they are perpetual foreigners."

For the full story, please visit http://www.npr.org/sections/itsallpolitics/2015/10/15/448718726/south-korea-trumps-where-are-you-from-moment.