John Luther Jones Sr from New Hampshire

I'm trying to get the correct father for John Luther Jones Sr . b 14 Aug 1874 in Hot Springs, Arkansas.  All my research says his Father was Nathan Jones, b. May 1855 in hot Springs, Arkansas, and his mother was Tabitha Lacey, b. 1855 in Tennessee.  All records like Census says Nathan Jones was black. 

The 1900 census says they (the whole family) are all black.

the 1910 census says the they (the whole family) are all mulato.

Other records say they're both.

But his parents, grand parents, gg grandparents and their spouses were all white.  so if they were all white, how is it that Nathan Jones is black?  unless I have the wrong Nathan jones, or it was put in the census' like that...  any help or suggestions will be, of course, appreciated.

John Paul Jones