Isaac Yarnall was the son of John Yarnall of Willistown. Will is dated November 3, 1785, and cites brothers Nathan Yarnall, Joshua Yarnall, and Caleb Yarnall, and sister Ann, the wife of Thomas Edwards. Will was affirmed Dec. 25, 1794 by Joseph Thomas & Josiah Lewis. Inventory of estate was taken by executors Nathan, Joshua and Caleb Yarnall on Jan. 17, 1796, with final accounting filed Nov. 7, 1798.