I regularly read about heritage language learners in North America. Who are they?

 

Dos this term refer to someone whose parents speak another language at home, or also someone who comes from a home where one of the parents speaks another language? What about someone whose grandparents spoke another language at home, but whose parents speak English at home? What about someone whose ancestry is, for example, Japanese, but whose parents came from Brazil and are Portuguese speaking , is the heritage Japanese or Brazilian? Just wondering.