Smith's mother grew up in Jamaica, and emigrated to England in 1969. Smith's parents divorced when she was a teenager. She has a half-sister, a half-brother, and two younger brothers (one is the rapper and stand-up comedian Doc Brown, and the other is the rapper Luc Skyz). As a child, Smith liked tap dancing. As a teenager, she considered a career in musical theatre. When she was a university student, Smith earned money as a jazz singer. She also wanted to become a journalist. Despite earlier ambitions, literature became her main interest.