As the director of Harvard's W.E.B. Du Bois Institute for African and African American Research, Gates' work often looks at this country's complex racial history. But it is not his scholarly work, which includes more than a dozen books, countless articles and documentaries, that has brought him the most recognition.

"When people stop me on the street, they don't say, 'Hey, I liked your latest book on literary theory.' They say, 'I love the genealogy series!' "

Still, the teacher in Gates has included lesson plans for elementary and middle school classrooms, which he hopes will use the series to teach history and science.

The first two PBS series focused solely on famous African Americans, but letters from viewers persuaded him to explore people of other races. The 2010 Faces of America included Meryl Streep and Eva Longoria, comedian Stephen Colbert and cellist Yo-Yo Ma.

"When I started the series, I thought the moving moment for my guests, in the case of the African-American ones, would be when I revealed what tribe the came from in Africa, but it wasn't. It was revealing the names of slave ancestors. People would cry," Gates said.

"Nobody cried when I told them what tribe they came from in Africa. They were intellectually fascinated but not emotionally engaged, as when you're looking at your great-great-grandparents and they were slaves."

Rep. Lewis, the son of sharecroppers who grew up on a farm in Alabama, had not done any exploration of his own into his family background. There had been been "conversations over the years with my mother and my grandparents, but they didn't go back too far."

Gates and his team were able to determine that Lewis' great-great-grandparents Tobias and Elizabeth Carter were given land and money when they were freed after the Civil War.

They also found Tobias Carter's name on a voter-registration form from 1867. It was during Reconstruction, when African Americans were briefly allowed the benefits of full citizenship, including voting and holding seats in Congress.

"I cried when that was revealed," Lewis said in an interview last week. "It was just unbelievable. Maybe it was something in my DNA or bloodline or whatever you want to call it, but I couldn't deviate from it ... I had to pursue it. That was so powerful for me, and I just cried."

It was through the efforts of activists such as Lewis, a leader in the Student Nonviolent Coordinating Committee, who in 1965 was nearly beaten to death by Alabama state troopers during a protest march for voting rights, that African Americans were again allowed to register to vote.

When he was growing up, Lewis said, his parents, grandparents and great-grandparents didn't have the right to vote.

"I have a greater sense of, I guess, selfhood. I know I come from a strong and determined people, and I think that's what made me much more determined and persistent," Lewis said.

He said he is eager to see the reaction of his brothers and sisters when they see the segment. "I probably will cry some more."

This article has been reprinted with permission by the Washington Post.

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