Sometime in the mid-1960's, John R. Rice published a booklet entitled "What Was Back of Kennedy's Murder?"
Dr. Rice explained that the wrath of God was on the descendants of Joseph P. Kennedy (father of President Kennedy) because of his success in selling alcohol in the US. Now, to be fair, everyone eventually dies, so it is no surprise that all Kennedys die.
But the assassination of Robert Kennedy, the disgrace of Ted Kennedy (who would probably have become President if he hadn't driven off a bridge with a woman who drowned), the death of John Kennedy Jr. (son of President Kennedy) in a plane crash, the death of David Kennedy (son of Robert Kennedy) from a drug overdose, the fatal accident of Michael Kennedy (another son of Robert Kennedy) in a skiing accident after disobeying orders from authorities, and the suicide of a Kennedy wife have made Rice's prediction look pretty accurate.
Throw in the many Kennedy tragedies before John F. Kennedy's assassination, and it looks like Rice was correct.
But the Kennedys are a very large family, and it could be argued that the unusually large number of tragedies are the result of chance.