The Brown family represented by DNA "Group 10" (of Essex Co., VA in the 1600s) at the Brown Genealogy Society DNA testing project website bought land from Robert King in Spotsylvania Co., VA in the 1720s. That was the same King family that later married into the Brown family of the John Brown whose second (apparently) wife was Nancy Cannifax.
The above is just one of several clues that make me wonder if that John Brown (and his apparent brother James Neville Brown....with both men being apparent sons of James Brown and Joanna Neville) were also part of DNA "Group 10." Just one of the other referenced clues is that there was a Daniel Brown in "Group 10" who married a Frances Neville (perhaps related to Joanna Neville?), and that Daniel Brown had a brother who was named Francis Brown (who married an Anna unknown)....and Francis and Anna Brown had a son who was named James Brown (could he have been the James Brown who married Joanna Neville)?
I wish that a living male Brown out of at least one of the sons of James Brown and Joanna Neville would take the Y chromosome DNA test.