Käthe was born to Recha and Hermann Stern in 1896 in the small town Arnstadt that can be found in the German federal state of Thuringia. There she spent her youth, eventually becoming the older sister of Arthur Stern who was born in 1901. In 1917, she married the merchant and company owner Ernst Schwab (1880 - 1966). Ernst shared with Julius Hirsch the ownership of the textile company Lewastrumpf in Chemnitz, Saxony, that produced both stockings and gloves. The couple therefore settled in Chemnitz where their two sons Hans Joachim (later Joel) and Peter (1922-2012) were born and went to school.

Following the ascent to power of the fascist NSDAP party and the imposed Nuremberg laws, Ernst and Julius were forced to sell the company and grounds below their value, before they and their respective families received permission to leave the country. Käthe's elder son Joel had managed to emigrate to the US and obtain entry permit for his parents. However, in order to take on the journey to the US, Käthe and Ernst had to temporarily stay in the UK that in the end turned out to be permanently. The couple found a new home in  Leicester where Ernst and Julius... (lacking concrete data and information concerning the couple's life in England - not to be published; work in progress)