Joanna Firestone was born in 1986 to Jewish parents Fred and Marilyn Firestone. Growing up as teenager, Jo would have cake baking competition with her friends including renowned pastry chef Claire Saffitz. She once won the competition with Box St. Louis butter vs. Claire’s $50 chocolate cake She has a brother, Ben Firestone, who works in commercial real estate. She grew up in Clayton, Missouri, a suburb of St. Louis. She graduated from Clayton High School and later Wesleyan University in Connecticut, with a degree in theatre.