Everyone Is Related. The (Big) Data Proves It

by Kasia Bryc Earlier this month, I was at the South by Southwest conference in Austin to speak on a panel with the writer AJ Jacobs, about how interconnected we all are.Kasia @ SXSW But walking around the conference with such a diverse mix of people – many with their rock star cool outfits and denim jackets – you’d be forgiven if you questioned whether they could possibly come from the same gene pool as me, a former nerdy high school kid. And yet, we really are all one big family. In June, AJ will host the Global Family Reunion in New York City, what he’s described as the world’s largest family reunion. AJ spoke about the many cousins he has found in his year of research. He was very proud of his family connection to Gwyneth Paltrow, and would welcome her to join his family for a kosher Thanksgiving. He also noted that he was related to Judge Judy, which caused him to revise his opinion of her – as a person – in a more favorable light. Also with us on the panel was Joanna Mountain, 23andMe’s Senior Director of Research. Joanna spoke about the incredible stories and discoveries that people have made by connecting to their DNA cousins. Such stories are regularly highlighted in this very blog. But I was most excited to show just how many cousins we all have. The typical 23andMe customer has over two thousand DNA cousins, and that’s just within the 23andMe database. It all comes down to the math: the further back – in generations – you go, the more genealogical ancestors you have. Two parents, four grandparents… all the way up to a 128 fifth-great grandparents. And that only takes you back about two hundred years. Imagine if you were looking for your ancestors from the sixteenth century, you’d have 131,072 genealogical ancestors to hunt down! So, as special as you are, all these many ancestors passed on their DNA not just to create you, but also your many cousins. And, as you can imagine, 130 thousand people have a lot of descendants, so it’s unsurprising that the average 23andMe customers can find so many cousins.Connections It easily follows that, with each of us having so many DNA relatives, any pair of individuals are connected through their cousins. To illustrate this point, I showed that each of Tuesday’s panelists, together with Prof. Henry Louis Gates Jr. (host of “Finding Your Roots” on PBS who kindly agreed to participate in my experiment), are all just one or two “cousin” connections apart. In fact, almost everyone in the database is connected through one, two, or three DNA cousins. Which should make you rethink how you treat anyone you meet on the street. Regardless of what they may look like, you never know who you might be related to!