John S. Ahn was baptized in the Pacific Ocean in 1957 in Korea and immigrated to America in 1959. He graduated from Chatham High School in New Jersey in 1961. John graduated from BYU with a B.S. ChE degree in 1966 and received his Ph.D. in ChE from the University of Cincinnati in 1970. As soon as he received his Ph.D., he was called on a mission to his native land, Korea, as the oldest missionary in his mission at the time. He also served as District President in the Korea Mission. Upon his return, he served as a Research Associate at the University of Utah. He joined E.I. DuPont Company's Textile Fibers Department the following year, 1973, as a Research Engineer. At DuPont, John worked in developing new acrylic fibers and polyester fibers such as Coolmax, Thermax, fiberfill products and other branded polyester fiber products. John was an internationally recognized expert in polyester fiber technology by the time he retired as a Research Fellow, a high ranking technical position at DuPont, in 2002.

Upon retiring from DuPont, he became a consultant for DuPont. DuPont eliminated its Textile Fibers Department in 2002 but outsourced some of its key products in Asia, and John was the key person in outsourcing these key products, such as the fibers used to make Thermax temple garments. He taught the Japanese, the Koreans, the Thais, the Indonesians, the Chinese and the Indians how to make high quality specialty polyester fibers for DuPont and its world-wide market. John is still consulting for DuPont in polyester fiber technology and is DuPont's only consultant in this area. John is also currently president of JSA Consulting Company.

John has served in various positions in the Church, including positions in the Bishopric, High Counselor, Stake Mission president, High Priest group leader, and Gospel Doctrine teacher.

John married Sonia H. Ahn in the Provo Temple in 1972. They have two daughters. His oldest daughter Charlene graduated in physics and mathematics summa cum laude from Harvard University and received her Ph.D. in physics from the California Institute of Technology, as did her husband David Beckman. She and Dave are currently employed at Toyon Research Corporation, a consulting company in California. His younger daughter Christina graduated from Stanford University in Chemistry with Distinction. Christina is completing her 4th year at Washington University Medical School in St. Louis. She is an Olin scholar - a 4 year merit scholarship at her medical school.