First, here's the marriage record for John & his wife Mary Ashton:
"Ohio, County Marriages, 1789-2013," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:XZX9-RL4 : 8 December 2017), John H Rardin and Mary E. Ashton, 14 Apr 1867; citing Athens, Ohio, United States, reference p 89; county courthouses, Ohio; FHL microfilm 311,593.
Note that his name was listed as "John H Rardin".
Second, the 1850 Census for Gallia, Ohio, includes a boy named John, who was age 6; born app. 1844. This family included an adult woman named "Celey Raridin", age 28; she may have been his mother. Other children included Harvey (age 3), Jacob (age 1), and Telis (age 16). The head of household" was "William Rander", age 29; Heritage Quest indicates several alternae spellings of his surname. William was born in Ohio.
I hope the other pieces of your puzzle come together for you!
Year: 1850; Census Place: Ohio, Gallia, Ohio; Roll: M432_681; Page: 373A; Image: 213