Joe Keller, the main protagonist in Arthur Miller's All My Sons, was a manufacturer of cylinder heads for the Army air force. Unfortunately, he knowingly shipped cracked cylinder heads to be used in planes causing the death of over 20 service men because of plane crashes. His greed for wealth and to leave the manufacturing business to his son was thwarted by the scandal and his deceit. Joe Keller professed to believe that family was important, especially when he wanted to leave his son, Chris, the legacy of a family business. However, his lack of concern in shipping defective parts killed other sons of families in America. I think "all my sons" refers to the fighting men who risked their lives during WWII. They are America's sons, so to speak. As soldiers, they lived and died for our freedom, and Joe Keller did not respect them. To Keller, it was more important to provide for his family than to protect the lives of others. His selfishness was his downfall in this story, and he lost everything because he failed to protect the sons of all Americans.