Wilhelm was growing up in parental estate located in Polish city of Żywiec, Kingdom of Galicia and Lodomeria. His father was a patriot of Poland and had inferior feelings towards Ukrainian population. Accommodating the 19th-century rise of nationalism, he decided that his branch of the Habsburg family would adopt a Polish identity and would combine a loyalty to their Habsburg family with a loyalty to Poland. Accordingly, he had his children learn Polish from an early age and tried to instill in them a sense of Polish patriotism. His oldest son, Karl-Albrecht, would become a Polish officer who refused to renounce his Polish loyalty even under torture by the Gestapo. Karl Stephan's two younger daughters would marry into the Polish noble families of Radziwill and Czartoryski.