Jan Frederiks Helfrich, born circa 1805 (?).

Jan was married to
Trijntje Klazes Fortuin, born circa 1809 (?).

• 1 : Klaas Jans Helfrich, born in Wonseradeel on April 16, 1832, worker and worker, died in Wonseradeel on September 14, 1913, aged 81 years.
  Klaas was married in Wonseradeel on April 21, 1859, at the age of 27 to Japke Dirks Ruim (aged 22 years), born in Wonseradeel on October 27, 1836, daughter of Dirk Rinses Ruim and Trijntje Tjerks de Vries, died there on January 19, 1912, aged 75 years.