I got this weird blue egg. How do we be racist against those aliens from that stupid movie I only saw fifteen minutes of before I got bored, space fern gully

Yeah I’m pretty sure chicken eggs, by definition, taste like chicken.

Chicken eggs do

That's your answer to everything

Ethnicity is useful for social categorization, but it cannot be used as a stand in for genetic Principle Components. Ethnicity is also a construct.

Then explain why Vin Diesel just took my pink slip!?

This is true, but I think people often don't even understand why race is a social construct, and what that means.

Race means something different depending on who uses the word and where.

If you, for example, read texts from 1920's Continental Europe, race is often used as a stand-in for nationality: "the German race", "the French race", "the English race" and so on. This is because "race" is a meaningless "us versus them" term. It's used to say "We are this, you are something else". It's used to glue together whichever group you determine to be the "in group" versus whichever group is the "out group".

In the USA, there weren't enough people of a specific nationality to form groups like that, instead the relevant groups were "us, the immigrants", "the native people", "the people from the next big political block in the south", "slaves" and "those other immigrants which we don't understand". So that's where we get "White", "Native Americans", "Latinos", "Blacks" and "Asians" from.

At the same time, when talking e.g. about humans versus animals, the term "the human race" was commonly used too. So a race could refer to anything from which language you speak, which nationality you are from or which species you belong to. It really doesn't mean anything at all.

In Europe, at the same time, the Nazis rose to power, and they were really clear on which race they thought was superior: Germans. They were not white supremacists, but German supremacists. They saw the English as a separate race and the white Americans as mixed-race race traitors. Which makes it kinda ironic that there are English and American neonazis. People the original nazis would clearly see as inferior.

After WW2 the word "race" fell out of use in most European languages (at least when referring to humans) and in the last few years it got reimported from the USA with the USA meaning of the term.

Incidentally, the term for "racism" did not fall out of use in Europe, so that still has the old connotations. This means that in German e.g. a German who hates all French people is a racist, while in US English he wouldn't be.