There is a living male Brown who shows his lineage back to Thomas Brown and Mary Pettus, and that man took the Y chromosome DNA test via the Brown Genealogy Society DNA testing project (which uses Family Tree DNA to do the testing). That donor has DNA that is a match to DNA "Group 26" at the Brown Genealogy Society website. At this point, it is difficult to understand just how the above Thomas Brown was "connected" to the Brown ancestors of the other donors who are also in "Group 26." See: http://brownsociety.org/browndna/results.htm
If anyone can determine just HOW any of the other Brown ancestors shown in DNA "Group 26" were related to the Thomas Brown who married Mary Pettus, please post that information here.
By the way, the Henry Brown who came into Lunenburg/Mecklenburg Co., VA from Essex Co., VA around 1761/1762 was a member of the unrelated DNA "Group 10." That Brown family married into the family of the "Robert Coleman of Mobjack Bay"....but DNA testing on various male Colemans has now apparently shown that the Cluverius Coleman who was so closely associated with Thomas Brown and Mary Pettus was NOT related to the family of the referenced Robert Coleman (note: that Robert Coleman family had married into the Grizzell and Spilsby families before they married into the "Group 10" Brown family).