CLUE
his wife's maiden name was Eskew
https://www.legacy.com/obituaries/greenvilleonline/obituary.aspx?n=vera-eskew&pid=140744710
more clues
https://www.familytreenow.com/search/people/results?first=Johnny&last=Blackston&citystatezip=South%20Carolina&dobyyyy=1936&rid=0s0&smck=ygBr8PtQBTBHOG-8yfyE2w
the obit was supplied by
https://www.umcsc.org/clergy/clergy-person-2440/
lists email - maybe he would tell who Johnny's parents were ?
census a no-result ; searched whole state
last resort - call library in Piedmont
http://www.andersonlibrary.org/location/piedmont/
see if it has 1936 newspapers on microfilm and can check for birth in paper