The 2016 presidential candidates are uniquely unpopular - why is that the case? Over the course of this special, NPR visits Hillary Clinton's and Donald Trump's personal histories and explores episodes in which their character was forged.

Examine key moments over the decades that helped cement their public reputations and hear the ways in which Clinton and Trump stood out from their peers even at a young age. Then, dive into aspects of their personalities that have turned into liabilities with voters: Clinton's need for privacy and Trump's desire for public attention.

To understand Clinton's character, NPR interviewed a close childhood friend, a former chief of staff, Republicans who worked with her in Congress, columnists who have tracked her career, and her daughter, Chelsea Clinton.

To understand Trump's character, NPR interviewed longtime friends in business, entertainment, and politics such as Piers Morgan and Roger Stone, a current business partner, a critic of Trump's business practices, and biographers.

Airs Sunday, September 11 at 12pm on AM820 and NJPR