Jan Siebs IJsma, born circa 1770 (?), died before September 7, 1816, aged at most 46 years.

Jan was married to
Lijsbert Jacobs, born circa 1774 (?).

• 1 : Baukje Jans IJsma, born in Arum circa 1797.
  Baukje was married in Almenum on September 7, 1816, at the age of approximately 19 to Jelle Theunis Tigchelaar (aged approximately 21 years), born in Almenum circa 1795, son of Theunis Reinders and Grietje Jelles, kilnman, tilebaker, worker, tilebaker and tigchelaarsknecht, died in Midlum on January 31, 1858, aged approximately 63 years.
  Jelle was married afterwards in Franekeradeel on June 29, 1828, at the age of approximately 33 to Johanna Jans Oosterhout (aged approximately 22 years), born in Harlingen circa 1806, daughter of Jan Johannes and Dieuwke Floris, werkbode.