After many rears of research I have (to my satisfaction) solved that mystery. He is the unknown son of Jeremiah Duvall born 1752 of Maryland. He married Sarah Penn, but he had an earlier wife. Jeremiah took pioneering families to Bedford Co. PA. The 1790 f census for his household shows two males under age 16.Not named in his will. Those by Penn are. Nimrod born 1777. Wife Rebecca Waters probably from Frederick Co. Maryland and a friend of Mary Pope Jackson, wife of Jacob LeFever of same area. I descend from Sarah Duvall b. 1822.