Well, I can't attest to the first two generations, but I can show you this marriage, which gives the names of Alexander's parents.

Ontario, Canada Marriages, 1857-1922
about Alexander Matheson
Name: Alexander Matheson
Birth Place: Scotland
Residence: Woodstock
Age: 31
Father Name: F. Matheson
Mother Name: Mary McVicar
Estimated birth year: 1833
Spouse Name: Janet Johnson
Spouse's Age: 18
Spouse Birth Place: Canada
Spouse Residence: Woodstock
Spouse Estimated Birth Year: 1846
Spouse Father Name: James Johnson
Spouse Mother Name : Jane Murray
Marriage Date: 15 Sep 1864
Marriage County: Oxford
Family History Library Microfilm: 1030062


I suppose it's possible that this is your Alexander, but there was nothing in the image to confirm that:

Name: Alexander Matheson
Death Date: 15 Mar 1897
Death Location: Oxford
Birth year: C1826
Birth Location: Scotland