I hate to rain on the "OMG, we're all going to hell in a handbasket, unlike in the good old days!" parade, but families have always been a part of the American politic.
Presidents John Adams and his son John Quincy Adams.
Presidents William Henry Harrison and his grandson Benjamin Harrison.
Presidents Theodore Roosevelt and his cousin Franklin Delano Roosevelt.
In fact, the current proportion of members of Congress (a far larger, and thus more useful pool, than the relatively small data-set of would-be Presidents) with relatives currently or formerly in Congress is lower than at any time since the late 1700s - because Congress was new then, and there were no former members of Congress to which one could be related.
For example, the Breckinridge family included 17 members elected to Congress (Henry Clay was one) and at least one member of the family was in Congress from the very 1st Congress in 1789 until January of 1978.
http://www.econ.brown.edu/faculty/Pedro_Dal_Bo/pd.pdf
Seriously. People are just noticing this?
Since 1988, five of the seven Republican nominees for President have been descended from a President (George W. Bush, son of George H.W. Bush), a Senator (George H.W. Bush, son of Prescott Bush) or a Governor (Mitt Romney, son of George Romney). Even Al Gore (Jr.) was the son of a Senator (Al Gore, Sr.).
And it's not like the electorate doesn't pointedly decline to support members of political families on a regular basis. Hillary Clinton lost in 2008. So did Evan Bayh that year, and Mitt Romney. Elizabeth Dole lost in 2000. George H.W. Bush lost in 1980.
While voting for someone on the basis of their relatives represents poor decision-making, so does voting for someone on the basis of another candidate's relatives.
It is all much ado about nothing.