"United States Census, 1880," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:M4GK-59G : 22 August 2017), Louisa Ennis in household of James Ennis, Beat 1, Lincoln, Mississippi, United States; citing enumeration district ED 29, sheet 33D, NARA microfilm publication T9 (Washington D.C.: National Archives and Records Administration, n.d.), roll 0655; FHL microfilm 1,254,655.
"United States Census, 1940," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:VBS8-SXD : accessed 18 May 2018), James P Dycess, Beat 3, Lincoln, Mississippi, United States; citing enumeration district (ED) 43-12, sheet 2B, line 43, family 27, Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012, roll 2045.
It may be possible to confirm family relationships with John by comparing test results with other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share DNA with John: