Why do you think that is Bruno's father is concerned about Lieutenant Kotler's family history?

Bruno's father is concerned about Lieutenant Kotler's family history because it reflects on the loyalty and values within the Nazi regime, which he is a part of. As a high-ranking officer, he is likely worried about any potential associations or implications that could undermine his position or reputation. Additionally, familial ties can reveal vulnerabilities or weaknesses that may affect their standing within the military hierarchy. This concern highlights the importance of loyalty and image in the context of their environment.