Ruth Seid was born on July 1, 1913, in Brooklyn, New York. She spent most of her youth in Cleveland, Ohio. Consisting of Russian immigrants, her family was Jewish and struggled to escape poverty. Seid also was a lesbian. She was the valedictorian of her high school class.
Upon reaching adulthood, Seid embarked upon a writing career. First, she wrote short stories and radio and television scripts to help support her family. When writing novels, she used the penname Jo Sinclair, and her works usually focused on class, racial, and homosexual issues. Her first novel, Wasteland, won the Harper & Brothers Prize for new writers in 1946. She proceeded to publish three additional novels, as well as her autobiography. Seid died on July 4, 1995.