Nuklo is the son of Robert Frank and Madeline Joyce, also known as the Whizzer and Miss America. He was born in the fictional town of Mount Athena, New York (where Project Pegasus is also located). The two retired from their careers as costumed crimefighters several years after the end of World War II, married, revealed their identities to the government, and took jobs at one of the nation's first nuclear power plants. When a radiation experiment went awry, the Franks rushed into a high radiation area to manually activate the damping rods that were malfunctioning and were exposed to massive amounts of radiation. Madeline Frank was pregnant at the time and when she gave birth eight months later, her son proved to be a mutant who emitted toxic radiation levels. Apparently, due to their own superhuman powers, the Franks were immune to the deleterious effects of excessive radiation. The Franks were persuaded by the government to place their infant son in a special capsule which would retard his aging process while draining him of excess radioactivity.