Tjerk de Jong, born in Harlingen on June 22, 1896, son of Eelke de Jong (barge hand, sailor, casual labourer, fisher and barge hand) and Fokje Tigchelaar (maid servant, jobless and shopkeeper), journeyman baker.

Tjerk was married in Harlingen on November 13, 1919, at the age of 23 to
Cornelia van der Veen (aged 22 years), born in Leeuwarden on March 13, 1897, daughter of Uilke van der Veen (bargeman and bargeman) and Geertje van der Wal.