Richardson was born on October 22, 1971 in Toronto, Ontario. Her mother, Susan Cuddy, was director of design and development for the old City of Toronto. Her father, Douglas Richardson, is a retired professor of history of art and architecture at the University of Toronto. Her brother, Theo Richardson, is also a designer and is a partner in the New York City firm of Rich, Brilliant, Willing. Richardson's parents divorced when she was five.