Thanksgiving gatherings could get bigger —a lot bigger—as science uncovers the familial bonds that bind us. From millions of interconnected online genealogy profiles, researchers have amassed the largest, scientifically-vetted family tree to date, which at 13 million people, is slightly bigger than a nation the size of Cuba or Belgium. Published in the journal Science, the new dataset offers fresh insights into the last 500 years of marriage and migration in Europe and North America, and the role of genes in longevity.