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Big Data Says You And A.J. Jacobs Are Cousins

AJ Jacobs on how big data is helping him build an enormous family tree


There’s the cousin you kinda dread sitting next to at Thanksgiving, and then there’s A.J. Jacobs. For his latest project, Jacobs, who’s best-known for his lifestyle experiments in Esquire and books such as “The Know-It-All,” “Drop Dead Healthy” and “The Year of Living Biblically,” is trying to build a massive family tree. As in, one that connects him to every person on Earth. And this Saturday, he’s throwing what he’s calling the world’s biggest family reunion.

Podcast: A.J. Jacobs on our podcast What’s The Point.

All this is possible because of major advancements in data, namely the plummeting cost of DNA sequencing, and the ability to connect huge family trees online through Wikipedia-style genealogy websites.

Jacobs recently stopped by the FiveThirtyEight studios to talk with podcast host Jody Avirgan about his project. Genealogy is “the most fascinating topic right now, because it affects everything in life. It affects family, and sex, and history, and what is the meaning of family and inheritance,” he said.

At the moment, Jacobs says the sequencing for ancestry is “relatively accurate,” but the sequencing for diseases is just “a little better than astrology.” Eventually, though, costs will continue to drop, accuracy will increase, and we will reach a point where there will be tons of health data available for every human, for better or for worse (Jacobs is surprisingly sanguine about our “‘Gattaca’-like future.”)

As for building his own family tree, Jacobs is able to work “sideways”1 and connect himself to thousands and thousands of people — and counting. Yes, President Obama is a “cousin” of A.J.’s — his aunt’s fifth-great-aunt’s husband’s brother’s wife’s seventh-great-nephew, according to — so are Quincy Jones and Eva Perón and Che Guevara. And so are you and I. These family trees will only continue to explode, says Jacobs, because of the changing nature of marriage and parenthood, a “radical shift” spurred by gay marriage, sperm donorship, three-parent children and more.

Watch the video above for lots more about the state of genealogy and A.J.’s project, and if you’re interested in his Global Family Reunion, you can read more about that on his website.

This conversation is a preview of a podcast/video series launching soon featuring conversations about how people in various fields are using data in interesting ways. Keep your eye out for What’s The Point on the site, on iTunes and elsewhere later this June!


  1. A strictly DNA-based genealogy would take into account only bloodline connections; Jacobs is incorporating marriage into his tree.

Jody Avirgan hosts and produces podcasts for FiveThirtyEight.