Johansson was born in New York City. Her father, Karsten Johansson, is a Danish-born architect, and her paternal grandfather, Ejner Johansson, was a screenwriter and director. Her mother, Melanie Sloan, a producer, comes from a Jewish American family from the Bronx. Johansson's parents met in Denmark, where her mother lived with Johansson's maternal grandmother, Dorothy, a former bookkeeper and schoolteacher. Johansson has an older sister, Vanessa, who is also an actress; an older brother, Adrian; a twin brother, Hunter, also an actor; and a half-brother from her father's re-marriage, Christian.
