Thorne is the daughter of immigrant parents, Nerissa and Navie Guy, who are originally from Trinidad. The actor grew up in New York along with her brothers, Ky-Mani and Caleb, while the rest of her family lived in Trinidad. She previously told Trinidad and Tobago Newsday, "Most of my family, actually, is in Trinidad. All my cousins and everything. It's only just really my immediate family that's here but at least 90 percent of my family members are still in Trinidad."
Despite living in the United States her whole life, Thorne is very immersed in Trinidadian culture because of her parents and family. Per her interview with Trinidad and Tobago Newsday, her favourite foods are Trinidadian classics like bake and shark, as well as crab and dumplings.