Narration: We wanted to know if our guests’ DNA could tell them something different about their ancestry. So I went to San Francisco to meet with Joanna Mountain, the senior director of research science at the genetic ancestry firm 23andme, to talk to her about doing what’s called an admixture test.

Henry Louis Gates Jr.: You can tell this man he looks like he has Native American and Asian ancestry, this man is African and European. You could tell him his percentage of African and European ancestry?

Joanna Mountain: Mmhmm I bet we could!

Narration: An admixture test reveals our ancestor’s geographic origins over the last several centuries – which means it can show us our ethnic breakdown. So we asked each of our guests to spit in a cup. Then we sent the samples to 23 and Me.

Gates: I am dying to find out the results of your genetic analysis for my guests. So can you walk me through each one?

Mountain: Well we’re looking at a lot of ancestry tracing back to Europe. This will be Meryl Streep.

Gates: Is there anything that you are particularly curious about?

Meryl Streep: Yeah, why I just have no melanin in my skin. None.

Gates: So do you think you have any African ancestry?

Streep: Um, it's possible, yeah.

Gates: Do you think you have any Native American ancestry?

Streep: Yes. I bet I do.

Gates: Well, here's the result. You have zero Native American ancestry. You have zero African Ancestry. You are 100% European.

Streep: See. I don't have to even bother to go in the sun. Gates: You, my friend, are a total, slam dunk,100% Asian.

Yo-Yo Ma: Man, I was hope... I'm so disappointed! So we are no longer bros?

Gates: No, we are bros. We're symbolic bros. I'm 7% Native American, remember?

Ma: Okay so there we go. We've got connections.

Stephen Colbert: The DNA Admixture results for Steven Colbert, 100% White Man.

Gates: You are 100%... you are the whitest person we have ever tested.

Colbert: All white roads eventually lead to me. I am the inescapable black whole of white people. So I'm not descended from a Chickasaw princess?

Gates: No, that be a myth.

Narration: I was struck that so many of my guests hoped to see more “ethnic” in their ethnic identities – more evidence of racial mixing in their personal pie chart. For the ones who were most mixed, the surprise was the way their results shifted their sense of who they are.

Gates: You, my dear, are 70% European, 27% Native American, which Asian and Native American are the same.

Eva Longoria: And 3% African!

Gates: There you go!

Longoria: Wow!

Gates: How do you feel about 3% African ancestry?

Longoria: I love it.

Gates: But Mexico, most people don’t realize, but had a huge slave population early on.

Longoria: People don’t realize that. A lot of people don't realize that.

Gates: If you could have written your own pie chart, what would the percentage have been?

Longoria: I would have written 70% Native American, indigenous to Mexico and 30% European. To know that I have Spanish blood in me, which I know that, everyone knows that in Mexico. But a majority of Spanish blood, is a little, ‘Oh!’ You know I’ve been so proud of like, you know, being Mexican. You know, Mexican from Mexico. You know, coming from the indigenous Native people. To know that that’s not really who I am…

Gates: It’s not ONLY who you are.

Longoria: It’s not only who I am, yeah. It’s a little, a little shaking to my foundation.

Gates: This is what you've been asking about all afternoon. This will tell you percentage of European, of Native American...

Elizabeth Alexander: My pie chart.

Gates: Your pie chart. You are 66% white! To what would you respond? Professor of African American Studies?

Alexander: It just gets curiouser and curiouser. But of course, you know if all of us were only known from our, by our DNA then we'd have a whole different American history.

Print Transcript