John Moore has a brother, William, also said to be born in Pennsylvania, who lived in Rockbridge County, Virginia. William's daughter, my 3g grandmother was born at Roaring Run in Botetourt, VA. In Botetourt County, Virginia Deed Book 14 pp 626-628, William and his wife Margaret sell land on Roaring Run to his brother John and wife Elizabeth. John is specifically named as William's brother. When I did DNA testing, I matched a descendent of John Moore of McMinn, Tenn (4th cousin). However, I have found nothing indicating who their father is, but then, I have not looked in Pennsylvania yet. Have you found anything in the time that has lapsed since you posted the request?
By the way, there are 2 More families in McMinn with similarly named men. Alexander really confused me for a while as both families have men about the same age.