Can anyone provide sources that go into much more detail about the material starting at around 39:05 of this YouTube video about the Celts? They're showing the showing the results of a genetic study on this topic.
Thanks!
(If there's a better sub to post this in I apologize)
You might also x-post to /r/AskScience: they may be able to direct you to the latest genetics studies and theories. /r/AskAnthropology may be worth asking also.