Dear Robert: It has been fifty years since your parents’ execution, and it is understandable that as the son whom their actions betrayed --along with their country--you should still cling to the idea of their innocence. But in the decades since 1953, we have learned much about your father, Julius Rosenberg, and the contributions he made to the Soviet Union as an active espionage agent. We also know, contrary to what you claim in your new book An Execution in the Family: One Son’s Journey, that your mother -- Ethel Rosenberg -- was not an innocent housewife as many of...