Re: Duncan's from Mason Co. W. V.
Not sure if this information will help you since you didn't specify the birth year for Isaac Duncan. However, I do have a list of children of George Allen Duncan b.1846 married to Sally Day Bodine.Their children; Nancy Duncan (m Douglas Byrn), Sarah Elizabeth Duncan (m. Willie Duncan), Robert Duncan, Bodine Duncan, Mollie Duncan, Isaac Duncan, Lucy Duncan, Henry Duncan.
Sorry I have no information on birth dates but would assume all children born around 1860-1880.
My line decends from William Mentlow Duncan, a brother of Goerge Allen Duncan.