The 1880 census at familysearch.org shows:
Van Buren County, Arkansas:

William Grant, age 49 born NC
with wife, Sarah, 49, b. MO;
and children:
Katie, 12, b. MO;
George W., 12, b. MO
William, 7, b. MO
in Davis TWS

I believe this family was in Scott County, MO in 1870, and if so it shows them with twin sons, then 4/12 old named:
George W. and John Mc.