John? Brown, born Abt. 173213. He married   Elizabeth Mercer? Bet. 1763 - 1764  . Elizabeth Mercer?, born September 22, 1732 . She was the daughter of 170. Robert Mercer II and  Ann Mounce. 

This is nothing more than a guess. I can find almost nothing on this couple other than their parentage of an Elizabeth who was the second wife of Job Gastineau. Nevertheless, they seem to have some connection to Pulaski county - - - Job [Gastineau] married 2nd Elizabeth Mercer Brown, daughter of John Brown and Elizabeth Mercer, c.1781, possibly in Maryland [Tibbals, History of Pulaski County, Kentucky, pp. 39-41; Ancestral File; Budd, Ancestors of George (Sr.) Gastineau].

She apparently was the daughter of John Brown & Elizabeth Mercer (who was a daughter of Robert Mercer II & Ann Mounce). George Mercer (Robert's brother?) was supposedly involved with George Washington in the Ohio Land Company (formed 1748). Child John Brown marrie Elizabeth bef. 1800 they had: dau. Mary Brown, born Abt. 1800; married Aaron Price January 02, 1816.

http://familytreemaker.genealogy.com/users/b/u/s/John-S-Bush/GENE18-0011.html http://familytreemaker.genealogy.com/users/b/u/s/John-S-Bush/GENE18-0009.html#CHILD16909314