When Jacob Kieffer was born on 21 February 1802, in Somerset, Shaw Mines, Summit Township, Somerset, Pennsylvania, United States, his father, John Jacob Kieffer, was 42 and his mother, Eva Margaret Fritz, was 32. He married Rachel Kimerer in 1822, in Somerset, Pennsylvania, United States. They were the parents of at least 8 sons and 6 daughters. He lived in Green Township, Wayne, Ohio, United States in 1850 and Chester Township, Wayne, Ohio, United States in 1860. He died on 5 March 1867, in Auglaize, Ohio, United States, at the age of 65.