When Jacob Jenks was born on 16 April 1760, in Smithfield, Providence, Rhode Island, United States, his father, Jesse Jenckes, was 25 and his mother, Mary Smith, was 22. He married Martha Mowry on 22 April 1781, in Smithfield, Providence, Rhode Island, United States. They were the parents of at least 6 sons and 4 daughters. He registered for military service in 1840. He died on 20 April 1842, in Saybrook, Ashtabula, Ohio, United States, at the age of 82.