Barack Obama is widely known as the United States' first black president. But is he really the country's first African-American commander-in-chief?

Of course author Toni Morrison famously declared that former president Bill Clinton was really the nation's first black head of state, however, rumor has it there are six other former presidents who had African-American ancestry: Abraham Lincoln, Andrew Jackson, Calvin Coolidge, Dwight D. Eisenhower, Thomas Jefferson, and Warren Harding.

Several scholars have discussed the genealogy of these presidents in the past, and the debate was reignited after Obama was elected in 2008.

Check out the slideshow at the link below for a list of former heads of state who allegedly were descendants of African-Americans.