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Speaker's Footnotes

Relevant notes and citations provided to TED by AJ Jacobs.

  • 02:16

    World Family Tree,

    When I gave my talk, there were 75,639,940 people on the World Family Tree on (which is a part of MyHeritage). Today, as I’m writing these notes, the tree has grown to 77,420,394.

    Another site, WikiTree, has a tree with more than five million relatives connected by blood or marriage.
    The word ‘tree’ is an excellent metaphor for these online organisms — they are constantly growing and changing.

  • 03:33

    A.J. Jacobs, "Are You My Cousin?," The New York Times, January 31, 2014

    These mega-trees, which as I say, will soon encompass most people on Earth, bring up thorny issues about accuracy and privacy. I address some of these concerns in an article I wrote for The New York Times, but they will continue to be flashpoints. Briefly, I believe the trees will never be perfectly accurate, but the more people who join and provide documentation, the more accurate these trees will become. The revolution in DNA sequencing will also help correct mistakes. As for privacy, the online trees usually obscure the names of living relatives, though it’s clear that some people will still be concerned.

  • 04:11

    Familinx, The Ehrlich Lab at MIT

    The scientific study of the Geni family tree is being done by Dr. Yaniv Erlich and his team at the Whitehead Institute, which is part of MIT. They are studying a bloodline within the World Tree with 13 million people on it.

  • 04:55

    To help show the interconnectedness, both Geni and WikiTree have introduced tools that allow you to track how you’re related to me. The sites can be accessed at, or I’m indebted to the hundreds of dedicated and talented researchers working on the World Family Tree and Global Family Reunion.

  • 05:39

    This chart is an idealized model of how many descendants you will have. The real number will likely be lower because some of those descendants will marry each other. Otherwise we would top 100 million people in 30 generations.
    Regardless, the number of our descendants is mind-blowing. There’s a phrase in Hebrew, “machatunim,” which means the parents of your children’s spouse, or co-inlaws. You and I are very likely machatunim of the future.

  • 06:50

    Kermyt G. Anderson, "How Well Does Paternity Confidence Match Actual Paternity?," Current Anthropology, June 2006

    As I mention, I’m related to Mary I, Queen of Scots through marriage. This brings up the question of blood relations versus relations by marriage. For my Global Family Reunion, I am taking an expansive view of family and including non-blood relations. I think increasingly this has to be the case. If you limit family to blood relations only, then it quickly becomes problematic. What do you do with adopted children? And gay couples who have children by sperm donors? And what about the phenomenon that genealogists politely call “nonpaternity events?” This is when the biological father of a child is not the one that it is thought to be. One study put the rate at about 2 percent, which means about 140 million people worldwide.

  • 07:35

    In addition to the millions of new cousins I got from the online trees, I also discovered thousands from DNA testing. You can order a kit from services such as and, spit into a tube, and then send them to the lab. You will be sent a look at your deep ancestry, along with a list of hundreds of cousins you probably didn’t know you had. According to 23andMe, I am distant cousins with my wife. I found this interesting. She wasn’t so happy.

  • 08:41

    Cass Sunstein, perhaps the world's most brilliant legal scholar.

  • 08:52

    My family is from Eastern European Jews, but my first cousin once removed married a man with WASPy roots, which allowed me to trace to President George H.W. Bush. Interestingly, all the presidents of the United States have now been traced to each other through Geni.

  • 09:11

    All proceeds from the reunion will go directly to battling Alzheimer’s disease, which affects 40 million members of the human family. I’m working with two organizations, the Cure Alzheimer’s Fund and Alzheimer’s Association.

  • 09:26

    The current record for largest family reunion is held by the Porteau-Boileve family in France, who had 4,514 family members in 2012. Since I am related to members of that family, all 4,514 of them are invited to the Global Family Reunion as well.