That information has long been accepted but is incorrect. David Hope Gavin was the son of James Gavin and Hester Carther.
Please see the 1860, 1870 and 1880 census records, as well as other records that exist in Franklin County.
There was a David Richardson Gavin who was born in the area and it is possible he was the son of John and Elizabeth Gavin, although I have no evidence of that. Also, purely speculative, is that James Gavin was the brother of John and that both were the sons of Thomas Gavin.
As well, there are children who were not listed in the original family histories, including Charles Collins Gavin, Mary Gavin Collins and Elizabeth Gavin Dooley.