When Isaac LeMasters III was born on 13 January 1806, in Archer Township, Harrison, Ohio, United States, his father, Isaac LeMasters Jr., was 32 and his mother, Jane Sprague, was 26. He married Ivy Miller on 21 February 1829, in Harrison, Ohio, United States. They were the parents of at least 2 sons and 4 daughters. He died on 17 September 1873, in Martin, Ottawa, Ohio, United States, at the age of 67.