Hello,
A Transcript of his marriage to Sarah McGee nee McDonald on the 30 Nov 1876, records John as born c1832, Bachelor, son of John Parsons - married to Sarah McGee nee McDonald, born c1847, widow, daughter of Sandy McDonald
Source: South Australia Marriages 1842-1937, Ref 109/280, viewed on Findmypast.co.uk
Sarah's marriage to Patrick McGee on the 31 May 1859 at Robe, lists her father as Alexander McDonald, and her year of birth as 1840.
Source: South Australia Marriages 1842-1937, Ref 109/280, viewed on Findmypast.co.uk
Regards,
T