I had kept your message posting in my email as "new" then forgot to reply I think.
The Proffitt/Prophet YDNA results of my David Wilkie/Wilkey ancestors' male descendants indicated the R1b1 Haplogroup, or western European. Many of the Celtic populations are in that group. Both of these male Wilkey cousins matched the YDNA results of a male Proffittt descendant Sylvester Proffitt of VA. As mentioned, my David Wilkie/Wilkey was the "bastard boy child son of Mary Wilkie which said child the said William Prophet stands charged of begetting" as written in the January 1784 court record in Wilkes Co NC.
William Prophet was son of John Prophet and grandson of Sylvester Prophet of VA. Mary Wilkie was probably born c1769-1770,
In my family tree, we spelled it "Wilkie". Sarah Wilkie born 1820 Wilkes Co NC was my ancestor (daughter of David Wilkey and Catherine Childers). Descendants of Sarah's brothers spell it Wilkey.
The Proffitt/Proffit/Prophet/Prophit surname seems to vary a lot. William Prophet's surname was later spelled Proffitt in later records. I'm not sure which spelling to use in my case.
Can you email me a family tree of your Mary Prophet and descendants? I can send you a link to mine online.