It would be great if a living male Thompson descendant of Rev. John Thomson, as well as a living male Thompson descendant of his POSSIBLE brother William Thompson, would take the Y chromosome DNA test. That will probably be the only way that we will ever know if those two men were or were not members of the same overall Thomson/Thompson family. We already have two male Thompson DNA donors who descend from the Mathew Thompson who died in Augusta Co., VA in 1753....but we do not know if that Mathew Thompson was or was not related to Reverend John Thomson and/or to the referenced William Thompson (though all of them seem to have been in PA earlier).
By the way, the daughter of Douglas Baker and Jane Thompson (Mrs. Jane (Thompson) Baker was a daughter of Rev. John Thomson) named Martha Baker married William Davidson, and they then lived in Botetourt Co. VA by 1769. That William Davidson was a member of DNA "Family 10" at www.davidsongenes.org
. The Major John Davidson and his mother Mrs. Isabella (Ramsey) Davidson (wife of Robert Davidson) who were mentioned in another post in this thread were, however, almost certainly not part of DNA "Group 10." Like the above Thomsons/Thompsons, we really also need a male Davidson DNA donor who "traces back" to Robert and Isabella (Ramsey) Davidson/their son Major John Davidson to see if such a donor should match any of the many exiting male Davidson/Davison/Davisson donors. Some suspect that the referenced Robert Davidson was a member of DNA "Family 1" (which included General William Lee Davidson who was killed at Cowan's Ford during the Rev. War), but there appears to be no "conventional documentation" that can prove or refute that "connection"....so a DNA test on a living male Davidson descendant of Robert Davidson/his son Major John Davidson (of "Rural Hill") is probably the "best last hope." Comments/questions?