George W. Risner b. 1816 TN but he's not a Risner.

My 2nd ggfa was George W. Risner b. 1816 TN.  However, he anglicized his very German name (shortened it and revised it) to spell it Risner.  And, after DNA testing results, he is not actually a Risner according to his genetics.  So, what was his surname??  There were at least 37 variant spellings that could be his German name that I've found so far.  The one I suspect is Rissinghoover on the census where he lived but apparently, this whole family also Anglicized their name as well with some even using the name Hoover.  This is very frustrating and knowing what trail to follow is very difficult.