His ancestors on his father's side were African slave traders. His ancestors on his mother's side were American slave owners. Of course, Obama doesn't want to talk about that any more than he wants to talk about his still never seen birth certificate.
"Barack Obama's campaign hired genealogists to research the family's roots at the onset of his presidential bid, but aides have largely kept the findings secret. Genealogists at Lowcountry Africana, a research center at the University of South Florida in Tampa, scoured documents to put together a 120-page report, according to project director Toni Carrier. She said the center signed a confidentiality agreement and is not allowed to disclose the findings publicly."
http://www.chicagotribune.com/news/local/chi-obama-slavery-01-dec01,0,485324.story
You can find a lot about Obama's American Ancestry online .
George Washington Overall and Mary Duvall were slaveowners.
Christopher Columbus Clark fought in a union unit, but Jefferson Davis was a relative.
Harbin Wilburn McCurry was also in a union militia. His family was said to have been attacked by Quantrill's raiders. More here.
Very interesting.