At the age of 13, he was legally adopted by his stepfather, who was Polish, and took on the surname Wilimowski. At home, he spoke German for the most part, while in public he often spoke a Silesian dialect of the Polish language. Officially a citizen of Poland, he referred to himself as an Upper Silesian ("Górnoślązak" - Oberschlesier).
At 13, he underwent formal adoption by his stepfather, who was of Polish heritage, and adopted the surname Wilimowski. In his family setting, German was predominantly spoken, whereas in public, a Silesian dialect of Polish was commonly used. As an officially recognized citizen of Poland, he identified himself as an Upper Silesian ("Górnoślązak" - Oberschlesier).