Roselyn was born in Johannesburg, South Africa, where she graduated from the University of the Witwatersrand with a B.Sc. in Math and Chemistry. She immigrated to the US when she was 23, and graduated from Cornell University with an M.S. in Mathematical Education. She taught Math and Computer Science for many years, mostly at Ithaca High School in Upstate New York. Roselyn retired from teaching in 2010. Since then she has worked full time as a writer. She lives in both Ithaca, New York, and Pasadena, California, with her husband, Saul Teukolsky.