The 2nd president of the United States, John Adams, was the father of the 6th president, John Quincy Adams, and the 41st president, George H.W. Bush, is the father of the 43rd president, George W. Bush. They are the only father and son presidents in the U.S.
John Adams and George H.W. Bush each served one term in office, and both lived to see their sons inaugurated as president. Both John Quincy Adams and George W. Bush entered the White House after contested election results, the former being elected by the House of Representatives, the latter after the Supreme Court ruling in Bush v. Gore.