The findings were part of a three-year investigation which uncovered the family’s use of slave labour during World War II.
According to the investigation, Albert Reimann Sr and Albert Reimann Jr used Russian and French prisoners of war as forced labour in their factories.
The Reimann businessmen were also openly anti-Semitic and supporters of Adolf Hitler, with the investigation finding a letter from Reimann Jr to a local mayor in which he complained that the French prisoners employed at his factory were not working hard enough and should be in prison, Deutsche Welle reports.
Findings from as early as 1931 show the family made donations to the SS, the military organisation under Hitler.
Reimann Sr passed away in 1954 and Reimann Jr passed away in 1984.
In a statement to German newspaper Bild am Sonntag, Reimann family spokesperson Peter Harf said the two deceased Reimann relatives were “guilty” and “actually belonged in prison”.
“We were ashamed and white as sheets. There is nothing to gloss over,” he added. “These crimes are disgusting.”
According to Harf, the elder Reimanns did not speak of their past anti-Semitic ties before they died, but family heirlooms prompted younger members of the family to commission a historian from the University of Munich to look into their past more closely.
Following the investigation, the Reimann family, which owns the majority of JAB Holding Company and which is reportedly one of the richest families in Germany, will donate $11m (£8.3m) to an undisclosed charity on behalf of the crimes of their ancestors.
The family also plans to make the findings public once the investigation has been completed.
The Independent has contacted JAB Holdings for comment.