Note from the Brantley Association on John Brantley and DNA testing: 

Update 2006

DNA testing shows that John Brantley of Nash County, is not a descendant of Edward Brantley of 1638 through a consistent male line. That is, he does not descend from him from father to son, to son, etc as we would expect.  Often grandfathers will adopt the children of a deceased daughter and rear them with their own name.  Since the Y-chromosome is handed down from father to son ONLY, it would not follow through the daughter. It is likely that John is a descendant of Edward, but DNA testing seemingly assures us that he did not descend through the generations from father to son.  Since he was no doubt tied either by adoption, if not by blood, to the Brantley family, his descendants are considered of the lineage of Edward.  The best news of this discovery, is that now we can identify his descendants by the distinct DNA profile as shown in others of his known descendants.  It has already shown that some proposed as his descendants were, in fact not, and others previously unknown in his lineage have now been identified as his descendants.  There are many more discoveries that will be made in the coming years as we find others among his many descendants throughout America through DNA testing.  (Brantley Association:  John Brantley of Nash County)