I often hear stories talking about how 8% of men in Asia are descendants of Genghis Khan based on modern genetic evidence and I was wondering if the historical record backs up or refutes this claim. What was Genghis family life and offspring producing life like according to historical sources?
hi! There's lots of room on the specific question of whether Genghis Khan had 100 sons, but general questions on the human genome and the inter-relatedness of living people are more up the alley of geneticists (/r/AskScience Biology category) and anthropologists (/r/AskAnthropology); this is the thread you really want ...
... but related questions are very common here too, most often in the context of Charlemagne, Genghis Khan, or William the Conqueror. The tl;dr is generally yes, vast numbers of people living today are the descendants of pretty much everyone (king or peasant) who lived in a general region that long ago. Here are the most recent posts on this:
and see this one, which has a longer explanation of the math involved, plus links to several other posts, including that AskScience AMA above
A couple of caveats when reading these threads, since comments are not always clear about what they are referring to:
"Descendants" are a given person's children's children's children's ... children. As a hypothetical example, imagine that after 2 generations he has 4 children (2 sons and 2 daughters), each of whom have 4 children (2 sons and 2 daughters): that's 4 + (4*4) = 20 descendants.
"Male-line descendants" are his sons' sons' sons' ... sons only. Using the above example, after 2 generations he has 2 + (2*2) = 6 male-line descendants (that is, his two sons and their sons; his daughters, his sons' daughters, and his daughters' children are excluded). This is the group that Y-chromosome DNA evidence refers to (see next point).
Y-chromosome DNA evidence does not prove descent from a him personally, but from people with genetic markers which he is assumed to have shared