I am a human being who can tell them they’re really bigoted for linking genetics with Japanese-ness. That line of thinking isn’t new at all, and it’s responsible for tragedies like miscegenation laws, eugenics, genocides, slavery, and (clearly) the demise of the native Japanese population for fear of immigration.

Of course people can believe that there’s a genetic component to Japanese-ness, and they are free to become extinct as a result.

I don’t care whether Japanese people agree or disagree with me, but if people in the US believe that genetics are important to nationality then there’s a problem. And yes HN is mostly a US forum.

Then immigration is not going to prevent Japan from a population collapse, I suppose to you that’s a reasonable end to the Japanese people.

Exception: if you're good at sports, you're Japanese, even if you barely speak a word. See Osaka Naomi and Lars Nootbaar.

I'm actually rather puzzled by what the dogmatic proponents of a multicultural population expect to be the end result, if not an inevitable convergence towards some bland, undifferentiated or trivially differentiated mean.

If this were to happen worldwide, and geography thankfully makes that likely impossible, I'm not sure that an entire planet blanketed with a single mass media driven culture, with the inevitable extinction of hundreds of long cultural tails ( like endangered or near endangered languages today) answers the problems that proponents of unrestricted multiculturalism seem to be profess concern about. For there to be cultural variation at all, "original" or "native" sources of variation to provide inputs for the "multi" have to be preserved somehow.

And it can't just be the cultural equivalent of farmers markets, reservations set up part time on half a city block, on land that 50 years prior was not city, but hundreds of acres of actual farmland and farmers tending it.