The bright yellow Zoo Pet Shop is hard to miss for anyone driving along one of the main streets that leads to the Auschwitz-Birkenau Memorial and Museum on the outskirts of Oswiecim, Poland. The store has been in Tomasz Borowski’s family for nearly 30 years and he’s gotten used to answering questions about living and working just blocks away from one of the world’s most notorious landmarks. The Nazis killed more than one million people at Auschwitz-Birkenau between 1940 and 1945, including Mr. Borowski’s great-grandfather, Jan Jakuczek. He was an officer in the Polish army who was imprisoned and shot...