Maybe the trouble with American politics is there's not enough new blood, literally. There are just too many marriages within the same gene pool. Here are a few examples.
Andrew Cuomo, who plans to run for Attorney General of New York, is the son of former Governor Mario Cuomo and is married to Kerry Kennedy Cuomo, sister of Robert F. Kennedy, Jr. They were separated last year.
Senator Barbara Boxer's daughter, Nicole Boxer married Tony Rodham in a White House wedding in 1994. Tony Rodham is Hillary Clinton's brother. They were divorced in 2000.
California Governor Arnold Schwarzenegger is married to Maria Shriver, daughter of Sargent Shriver whose wife is Eunice Kennedy Shriver whose mother is a sister of President John F. Kennedy.
John Kerry took a run at marrying into the Kennedy clan in 1962 when he dated Janet Jennings Auchincloss, Jacqueline Kennedy's half-sister. That romance didn't go any further, but Kerry would later marry Teresa Simoes-Ferreira Heinz, best known as heiress to the ketchup fortune. But Teresa's deceased husband, H. John Heinz, was also a U.S. Senator from Pennsylvania and a Republican.