Young children, adolescents, and men and women in their prime reproductive years may now survive for decades after cancer. They and their families celebrate these medical advances and hope that after cancer treatment ends, they can resume what Kathlyn Conway described as “ordinary life” [1]. When patients and their families learn that the treatments for some cancers can impair their fertility, they may feel that they will not be able to look forward to that ordinary life. No wonder, then, that many adult patients and parents of adolescents will rejoice at the medical and scientific developments that someday might permit them to have their own genetic children.