Klaas Sybes Kooystra, born in Wartena on February 11, 1817, son of Sybe Klazes Kooystra (barge hand and bargeman) and Antje Uiltjes Veenema.

Klaas was married in Idaarderadeel on September 5, 1845, at the age of 28 to
Aaltje Jans Gorter (aged approximately 22 years), born in Grouw circa 1823, daughter of Jan Taekes Gorter and Sibbeltje Durks Grouw.