Paul Fronczak discovered that he was not biologically related to his parents, Dora and Chester Fronczak, but was born in New Jersey as Jack Rosenthal. He also learned he had a twin sister, Jill, who was missing. Paul's search for his identity had expanded. He was now looking for three people: the real Paul Fronczak who was kidnapped in 1964, the kidnapper, and his biological twin sister, Jill. 

Referenced in the episode:  

Paul Jack Fronczak's podcast: The Fronczak Files

Paul Jack Fronczak's books: The Foundling and True Identity 

Documentary: The Lost Sons