William M. Lumpkin/s, b. abt. 1801 VA /TN/TX, Parents?

I am searching for the correct parents of William M. (Moore?)Lumpkin/s who was in Texas as early as 1832, recieved a Mexican Land Grant (Abstract No. 39)in Nacogdoches,TX, has Character Certificates for land grant applications, is listed with wife Paulina, and children in first census of Texas, is listed on San Augustine Co. TX tax rolls from 1837-1848, and is in 1850 San Augustine Co. TX census:
Wm. M. Lumpkins 49 VA, Polina 38 Ky,Christney 21 TN (my gg gm, married John Williams), John 20 TN, David 18 TN, Wm16 TX, Elizabeth 13 TX, Nancy 8 TX, Martha 6 TX, George W. 2 TX.
I have, erroneously I think, assumed that my William was the son of Robert Lumpkin and Elizabeth Forrest.Now I think I may be wrong.It is possible that he is son of John Woodson Lumpkin and Elizabeth?.Can anyone assist me in finding the truth or the best bet?