Hi all - have recently restarted a long lost passion(addiction lol) for discovering our family history  

My GGF JOHN GRANT has been a real bug bear to trace so i was delighted to finally "find" him a few weeks ago in the Scottish 1871 census.
As I am in Australia it has been a huge help having the census data online now.
Anyway this is the info that was listed:
Registration District - Dunbarney    Address  -  Ballendrick, Dunbarney         County - Perthshire
Piece 347     Foilio 4     Page 2    Civil Parish Dunbarney
James Robertson -        Overseer              Head           Married     Male       53      DOB 1818     Born Dunbarney, Perthshire
Janet Robertson -         Overseers wife     Wife            Married     F             57              1814              Forteviot, Perthshire
Margaret Robertson -   Dressmaker          Daughter       u/m        F             20               1851             Dunbarney
James Robertson -                                    Son                u/m        M             17              1854             Dunbarney
John Grant                                                Grandchild                    M              2               1869             Dunbarney
Given the ages of James and Janet - I am sure they had other older children that were not living at home, however I ran out of credits (lots of them) before managing to find them anywhere on the 1861, 1851 or 1881 censuses.
I am 99.9% certain this John Grant is the right one. The location is exact to what i already know and the name Robertson does run in the family (good old Scottish naming lol) I'm assuming he was the son of an older daughter who married a Grant or could poor little Margaret the dressmaker be his unmarried mother? If so why give him the name Grant?
There was a rumour gleaned from old John before he died to my grandmother  that he was perhaps an illegitimate child.
He married Elizabeth Ross in Dunfermline in 1892 and they emigrated to Australia in 1912 with their 4 children.
I have no idea if John Grant had any siblings - as far as i know he was an only child.
Would really love to hear from anyone else researching this particular line of Robertsons (yes i know its such a common name as are James and Janet lol)
Thankyou for reading
Cheers
Sonya