It wasn't my intention to limit my comments on this to statements for which I have links to supporting academic studies. I wanted to propose my guesses, because it's fun to see who else has arrived at the same spot. I was careful to start with "I think it's" rather than "it is true that" or "consensus exists that".

Your "I think" described the conclusion. I didn't read it as describing your explanation for that conclusion, which you seemed much more confident about.

How can you say that for certain? We don’t understand genetics well enough yet (much less anything downstream of that).

The comment discussed a survey of humans alive today.