What would you do if one day you discovered you have 13 million cousins? I’ll bet it would impact your Christmas gift giving immensely, but how would it affect your state of mind?
Well, last week a group of genealogists have discovered a family tree with 13 million relations. And you could be among them, somewhere out on a limb! This means that there is one family out there whose relatives could fill the countries of either Sweden, Greece, Portugal, Belgium, Jordon, Austria, Denmark, or Israel, with a few million relatives left over to birth their own country.

“Through the hard work of many genealogists curious about their family history, we crowdsourced an enormous family tree — and boom — came up with something unique,” said the study’s senior author, Yaniv Erlich, a computer scientist at Columbia University. Erlich is also the chief science officer of the genealogy and DNA testing company, MyHeritage, that owns Geni.com, the platform the hosts the data used in this study. The study was published in the journal, Science last week.

The research team analyzed records from 86 million Geni public profiles spanning an average of 11 generations, over 500 years, with 85% of the subjects originating in Europe and North America, then looked at migration patterns and how they influenced marriage. There were also a few remarkable incidental findings as well.

What the research found

In addition to the trends regarding marriage and migration, the study shows “the power of leveraging personal ancestry data to get all sorts of novel information, [which] nobody really thought of before,” said Mark Stoneking, a professor of biological anthropology in Leipzig, Germany, who was not part of the study but is interested in its implications.

Here are some of the findings:

  • On the average, “good” longevity genes can increase someone’s lifespan by an average of 5 years.
  • Prior to 1750, most Americans found their spouses within 6 miles of their birthplace.
  • By 1960, Americans found their spouses within 60 miles of their birthplace.
  • Men have migrated or moved significantly farther than women.
  • Women migrated more than men.
  • Advances in technology and transportation coincided with longer migrations.
  • Those who were of marrying age during the 19th century, tended to marry into family more than their predecessors did.

From 1650 to the beginning of the 19th century, the average married couple in Europe and North American were 4th cousins.

Not everyone agrees with the interpretation of the data and it is therefore leaving some researchers debating the definitions of longevity and the role big data is playing in the study. Some say more controls are needed. Others remained pleased with the results and hopeful about its implications. Regardless, the 13-million-person is available for curiosity seekers and for those involved in academic research at FamiLinx.org, the website created by Erlich and his colleagues. Take a look. You just may find a find a long-lost rich aunt there who needs an heir.


1. Family tree linking 13 million people reveals story of migration in Europe and North America.

2. Quantitative analysis of population-scale family trees with millions of relatives. Science.

3. The 13 Million People in Your Family Tree. The Wall Street Journal.