COLUMBIA, S.C. -- The biracial daughter of the late Sen. Strom Thurmond defended the former segregationist on Tuesday and said the Rev. Al Sharpton "overreacted" when Sharpton learned he is a descendent of a slave owned by the senator's relatives.

"In spite of the fact he was a segregationist, he did many wonderful things for black people ... I'm not sure that Reverend Sharpton is aware of all the things he did," said Essie Mae Washington-Williams, who was in South Carolina for a speech. "I kind of feel that there was an overreaction."

Professional genealogists working for Ancestry.com found that Sharpton's great-grandfather Coleman Sharpton was a slave owned by Julia Thurmond, whose grandfather was Strom Thurmond's great-great-grandfather. Coleman Sharpton was later freed.

When Sharpton learned of the link, he said: "It was probably the most shocking thing in my life."