When Leo Adam Finster was born on 26 June 1887, in Donnersdorf, Schweinfurt, Bavaria, Germany, his father, Franz Nikolaus Finster, was 23 and his mother, Anna Maria Wilhelm, was 22. He married Philomena Reinhart in 1918, in Donnersdorf, Schweinfurt, Bavaria, Germany. They were the parents of at least 2 sons and 3 daughters. He died on 4 November 1956, in his hometown, at the age of 69.