Leon Issert was born on June 17, 1931 to Marie Ange "Angie" and Jules Issert in Peotone, Illinois. He attended a one room school house for six years before entering Notre Dame Academy in Bourbonnais, Illinois for two years. He graduated from Notre Dame Academy in 1945. In 1949, Leon graduated from Peotone High School and then attended St. Bede College in LaSalle-Peru, Illinois for one year. In 1940, Leon entered the University of Illinois for three years. Leon graduated from the U of I in 1953 with a degree in Agricultural Economics.
From 1954 – 57, Leon served in the United States navy and rose to the rank of lieutenant gunnery and engineering officer. His naval service included tours of duty on aircraft carriers and cruisers in the Pacific Ocean. On November 11, 1972, Leon married Rosellen Garnier. They have two daughters, Nicole and Elizabeth. In addition to working full-time on the farm that has been in his family since 1903, Leon likes to snow ski. At the end of 2005, he and his two daughters visited French relatives on an extended tour of France.