Quantitative analysis of family trees with millions of relatives (2017) [pdf]

And, of course, the most important result of the paper is 13 million degrees of Kevin Bacon:

"The largest family tree in the processed data spanned 13 million individuals who were connected by shared ancestry and marriage (Fig. 1C). The tree included public figures such as Kevin Bacon..."

Better to link the final version - http://sci-hub.la/10.1126/science.aam9309