third culture people
n.— «These schools, for children of expatriates, teachers, diplomats, corporate executives and missionaries, are all over the world and most use English as their main language. The children and their parents are often referred to as “third culture people,” individuals who spend most of their time outside their passport country.» —“Tales to Inspire the Expatriate Young” by Marc Levitt New York Times July 3, 2007. (source: Double-Tongued Dictionary)