Hi Elsie
Firstly on James Carruthers and Mary McBain. This looks like their marriage on IGI:
JAMES CARRUTHERS Marriages: Spouse: MARY MCBAIN
Marriage: 31 MAY 1867 Kelton, Kirkcudbright, Scotland
They looked to have move to Renfrew shortly after their marriage. These are the children showing for on IGI, including John:
1. ELIZABETH CARRUTHERS Birth: 16 JUL 1869 Kirkcudbright, Kirkcudbright, Scotland
2. JOHN CARRUTHERS Birth: 02 MAR 1873 Kilmacolm, Renfrew, Scotland
3. GEORGE CARRUTHERS Birth: 12 APR 1871 Kilmacolm, Renfrew, Scotland
The 1871 Census entry for the family in Kilmalcolm is a mess in terms of transcription

I'll leave it as is, you will have to view the original for accuracy:
James Canutson 25, Porter Radsoy, b. ??, Kirkenthyke
Mary Canutson 26, b. Kelton Certedoyeas, Kirkenthyke
Samuel Canutson 3, b. Kelton Certedoyeas, Kirkenthyke
Elizabeth Canutson 1, b. Kelton Certedoyeas, Kirkenthyke
Address: Burnside Road, Kilmalcolm
The family in 1891, all children b. in Kilmalcolm. John not showing in the household. Can't see him easily in the census index, not sure how he has been transcribed:
James Carruthers 46, coal agent, b. Minnigaff, Kirkcudbrightshire
Mary Mcb Carruthers 45, b. Castledouglass, Kirkcudbrightshire
George Carruthers 19
James Carruthers 16
Jane Carruthers 11
Agnes Carruthers 7
Address: Port Glasgow Rd 2 Burnside House, Kilmalcolm
Regards.
Monica