The largest ever family tree with over 13 million people has been created by researchers according to Science magazine March 2018. They have looked into the genealogical history of UK, Europe and North America. The enormous record is slightly less than the population of the Commonwealth country of Zambia and illustrates 500 years migration across the Atlantic.
http://science.sciencemag.org/content/early/2018/02/28/science.aam9309#