Bob, I believe it is quite likely that your Smith, born 1821, is a son of Clayton Abernathy, born circa 1795, died post 1860 in Wake County, NC.Clayton had an older brother named Harbert, born circa 1784 and both were the sons of Smith Abernathy, died 1842 in Wake County, NC.Harbert (my ancestor) married Polly Davis in February 1810 and had the following sons that I know of: Clayton, Davis, John M. and William. Harbert only had these four sons that I know of and census records appear to corroborate this.Harbert & Clayton's father, Smith (d. 1842), had two much younger sons by another wife, Josiah B. and Robert D., that were about your Smith's age, though a little older, but they are the sons listed in the 1840 Smith Abernathy household in Wake County.That only leaves Clayton Abernathy (b. ca. 1795) in the Wake/Chatham area who might be a candidate to be your Smith's father. Clayton married in 1820 to Matilda Ligan (Logan-?) in Wake County.He had a son according to the 1830 and 1840 censuses that would fit your Smith, born 1821.He & Matilda also had a son name Sidney S. Abernathy, born circa 1833, who served in Company I of the 55th Regiment of NC Troops.
Merry Oaks is in the southeast corner of Chatham County.many of my ancestors lived in that area in the 1800s: Mann, Abernathy, Holt, Sloan, Goodwin, Upchurch, Peddy, Womble, Marks and Harrington.