You said this is your family line

Jakob Klaasen Goris m. Jantje Cornellis
(father)Klaas Jacobs m. Geertje Harms Goris

Geertje is not a Coris

Here is a death record for the brother of Jakob

Source Civil register - Death
Archive location Groninger Archieven
General Municipality: Ulrum
Type of record: overlijden
Record number: 33
Registration date: 10-04-1824
Deceased Jan Klasen Goris
Gender: M
Date of death: 08-04-1824
Age: 44
Place of death: Vliedorp gem. Ulrum
Father Klaas Jakobs
Mother Geertje Harms
Partner Klaaske Jans
Relationship: weduwnaar
Additional information geboortepl: Vliedorp gem. Ulrum; beroep overl.: daglooner; beroep vader: timmerman

Thus his parents are
Father Klaas Jakobs
Mother Geertje Harms