finding your roots

3 Degrees of Separation, Part 2

Genealogy Team June 8, 2012

While the PBS series Finding Your Roots made only passing reference to connections between guests, the truth is that each guest is separated from each other guest by at most three degrees — genetically.

Three Degrees of Genetic Separation

What the graph above shows is a simplified view of just some of the connections between guests on Finding Your Roots. We’ve cut out most of the interconnections because otherwise it would look like an unintelligible ball of yarn. In actuality, every guest is connected to every other guest and in fact, any two people who have been genotyped and filed in a particular database can be connected to each other — or to a Finding Your Roots guest — through one or two 4th or closer cousins.

By tracing paths through related individuals in 23andMe’s database, we learn that Harry Connick Jr., Robert Downey Jr., and Barbara Walters are all direct cousins, that Martha Stewart and Samuel L. Jackson have a mutual cousin, and that Condoleeza Rice, Cory Booker, and Geoffrey Canada each share a mutual cousin with Kevin Bacon.

This concept of “three degrees of genetic separation” is a result of increased human migration across the globe. As people from different geographic regions traveled and mixed over the last 500 years, the genetic distances between people also shrank. Go back in time, and the corresponding distances between any two people may have been more like eight or nine genetic degrees.

Angela Buchdahl represents a genetic “bridge” between her Korean and Ashkenazi Jewish heritages, linking people like Margaret Cho to Barbara Walters. Barbara Walters herself must have also had many ancestors that spanned different regions and populations, as she represents common links between Angela Buchdahl, Kyra Sedgwick, Robert Downey, Jr., and Harry Connick, Jr.
About the Authors:
Scott Hadly is a writer with extensive experience as an investigative reporter. Currently Mr. Hadly is Content Editor at 23andMe, Inc.

Shirley Wu completed her Ph.D. in Biomedical Informatics at Stanford University and now oversees 23andMe’s pipeline of detailed health reports and health-related features. She also contributes regularly to 23andMe’s blog. Currently Dr. Wu is Science Content Manager at 23andMe, Inc

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  • Cynthia Lewis

    June 18, 2012 at 9:33 pm

    Dr. Gates,
    I have been fascinated by watching your series “Know Your Roots”. I was particularly interested in the segment on Sanjay Gupta shown on 5/6/12. I believe you showed him his family tree with multiple generations on one document. I’m trying to do my family tree but I’m having a hard time printing 7 generations onto one document. I’m using Family Tree Maker, is there another software that would allow me to print 6-7 generations with several different branches of the family? I love the show and look forward to the interesting things I find out on your shows.
    Cynthia Lewis

  • Cynthia Lewis

    June 19, 2012 at 12:11 pm

    Correction: series Finding Your Roots.

  • Edwin Rowe

    June 25, 2012 at 4:42 pm

    Actually, the article is mistaken. Barbara Walters did not have ancestors who spanned many different genetic populations. The show itself revealed her genetics to be 91.8% Middle Eastern based on her Jewish ancestry. Harry Connick, Jr., Margaret Cho, Robert Downey, Jr., and Angela Buchdahl all have some degree of Jewish ancestry. That is the common genetic aspect that links them all.

  • Carol Dobson

    June 26, 2012 at 1:29 am

    I hope that soon we’ll see the rest of the series. I’ve enjoyed every one of them.

  • Allison Sears

    July 14, 2012 at 8:20 am

    I can’t thank you enough for your program! I wish so very much that we could have your stories go to every school and university across America!

    We are connected – we all belong to The Family of Man. Our very blood – our DNA proves it. We all have:
    …..I had a fun thought of using GATC to “Scientifically Connect” us all.
    Use it as a “word”: (Pronounce: G-A -T – “S”, long “A”) You GATC the idea that you are fantastic? You GATC it all to stand tall!…The scientists say so, so it must be true. You GATC to know that you are perfect, you are out-standing, your DNA proves it…….etc! Just “play” with the idea/ the word: it’s inspiring and can lift people up to help us “Connect”. Inspire kids!
    Our country really needs this information: we shouldn’t fight! We must come together – for America!
    Your show proves it. You ARE making a great difference FOR AMERICA!
    I can’t say thank you enough for all of your efforts and care for THE FAMILY OF MAN!

  • Crystal

    July 26, 2012 at 8:44 pm

    I have African, native American and Irish ancestory. I have recently been told that a story from family lore is true and that my Great Grandmother was a realted to Sitting Bull. Her name was “Walks Fast Or Forward” Helen Brown is her American name. After watching “Finding Your Roots” I am keen to get further proof and I know a DNA test could do that.

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About the Series

The basic drive to discover who we are and where we come from is at the core of the new 10-part PBS series Finding Your Roots with Henry Louis Gates, Jr., the 12th series from Professor Gates, the Alphonse Fletcher University Professor at Harvard University and director of the W.E.B. Du Bois Institute for African and African American Research. Filmed on location across the United States, the series premieres nationally Sundays, March 25 – May 20 at 8 pm ET on PBS (check local listings).

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