Sobieski was born Liliane Rudabet Gloria Elsveta Sobieski in New York City, the daughter of Elizabeth, an American novelist and screenwriter who also works as Sobieski's manager, and Jean Sobieski, a French painter and artist who appeared in French and Italian spaghetti Westerns during his youth, as well as dated actress Jean Seberg. Sobieski's first name, "Liliane", was the name of her paternal grandmother. Sobieski has a younger brother, Robert, who attends Princeton University. Sobieski's maternal grandfather, United States Navy captain Robert Salomon, was Jewish and Sobieski grew up in a "pan-religious" family; she has said that she is "proud of [her] Jewish roots". She has stated that her "...great great granduncle" was John III Sobieski, one of the elected kings of Poland who saved Europe by riding West with the Polish army in 1683 to lift the siege of Vienna from Ottoman Turks. Sobieski speaks fluent French, although she does not speak Polish. Her father currently lives in France.