In the record for John Fanning in his 1870 marriage with Marguerite McPadden and 1874 marriage with Eliza McCarthy, his parents are named James Fanning and Catherine Fortune and his place of birth as Wexford. It's not yet been possible to trace anything about James Fanning and Catherine Fortune. beyond a few clues in information about John Fanning.
In the marriage announcement for John Fanning in the marriage to his first wife Marguerite McPadden it described him as the younger son of the 'late James Fanning'. From this it's possible to date James Fanning's death to before 1870 and recognise that John Fanning had siblings. Another clue is that John Fanning's baptism in 1844 would mean that his parents were married before this year.