Genghis Khan's genetic legacy lives on in over 16 million men today. An international team of geneticists found that almost 8% of men in areas once part of the Mongol Empire carry a Y-chromosome type that can be traced back to Mongolia 1000 years ago. This suggests that Genghis Khan, who killed 40 million people as he built his vast empire from Asia to Eastern Europe, also left behind a large genetic footprint through his documented preference to rape and loot women from conquered lands. The Y-chromosome is passed from father to son essentially unchanged, allowing geneticists to use mutations to identify unique patrilines originating over 1000 years ago that likely include Genghis Khan's.