Sierra was born in Iowa, and Bianca was born in Hawaii. When Sierra was about 5 years old and Bianca 3, their parents separated. The girls lived with their mother, an artist and singer of Native American and Syrian ancestry. They moved to new towns almost every year, living in Hawaii, California, New Mexico, and Arizona. Because their mother believed that the girls would learn more doing art in the "real world" than in school, neither sister finished high school. Their Mother nicknamed her daughters "Rosie" (Sierra) and "Coco" (Bianca), from which the musical act takes its name. Their father, an Iowa farmer interested in Native American spirituality spent summers with the girls on various Native American reservations taking part in gatherings and ceremonies. In 1998, at about age 18, Sierra moved to New York City, then to Montmartre district in Paris two years later to pursue a career as an opera singer, studying at the Conservatoire de Paris. During this period, Sierra lost contact with Bianca, who was living in New York City studying linguistics sociology, and pursuing her passion of visual arts and writing. CocoRosie started making music together in Paris in 2003. Their first album, La Maison de Mon Rêve came out in 2004, then Noah’s Ark in 2005, The Adventures of Ghosthorse and Stillborn in 2007 and then Grey Oceans. They like to explore the world, travel and create.
