Her parents were Chaim Hersch Korngut and Rosa Rachel Blumenstock, a Jewish family originally from Poland.

In Berlin, Sieradzki worked as a bank teller, and eventually married Mendel Szydlow.

[2] On September 12, 1942, Sieradzki's husband Mendel Szydlow was arrested on the street in Antwerp and deported to Auschwitz-Birkenau, where he was murdered.

Sieradzki suffered from tuberculosis, and was admitted to the Sint-Erasmus hospital in Borgerhout (Antwerp), where she survived the rest of the war.

In 1954, the family moved from Antwerp, Belgium to Montreal, Canada, where she lived till her death in 2019.