Thomas Edelmann was born in Germany more than 25 years after the Allies defeated Hitler. Yet last year, following an unexpected marketing call, the 49-year-old businessman contacted a retired teacher in Israel to apologize for the actions of the grandfather he never met. Growing up, Edelmann had heard rumors about the family business and suspected it had previously been owned by Jews who were forced to sell to his paternal grandfather, Wilhelm. In recent years, the father of two had begun to dabble in genealogy. He came across Nazi tax records confirming that the Jewish owner -- Benjamin Heidelberger --...