Þorsteinn Jónsson was born in Eyjafjarðarsýsla on June 6, 1870.
Spouse: 1) Guðrún Þórðardóttir b. 1870 in Eyjafjarðarsýsla, d. August 3, 1903 in Winnipeg. 2) Sigríður Sveinsdóttir b. August 18, 1868 in Eyjafjarðarsýsla, d. in Bellingham on February 12, 1916 3) Sigurborg Þorláksdóttir b. June 13, 1898, d. February, 1965.
Children: With Guðrún: 1. Þóra b. 1894, d in Winnipeg 1903 2. Jón b. 1895 3. Sigurlína b. 1897, d. in Winnipeg 1903 4. Lára b. 1900, d. in Winnipeg 1903 5. Fanney b. 1901. With Sigurborg: 1. Ásgeir b. March 17, 1920 in Wynyard 2. Steingrímur b. July 15, 1924 in Hnausa 3. Stefanía b. June 13, 1927 in Hnausa 4. Lárus b. May 22, 1930 5. Violet b. 1932.
Þorsteinn came west to Winnipeg, Manitoba in 1902. A year later, he lost his wife and three children. He moved to Saskatchewan and farmed near Leslie in the Vatnabyggð Settlement. He moved from there to the Hnausa Settlement in Manitoba in 1924 and settled in Árnes in 1928.