This story reminds me of that episode on the TV show, The Orville. Season 1 Episode 9. Both the Navarians and Bruidians lay claim as the planet's original settlers. An ancient artifact containing residual DNA is discovered. They agree to a neutral third party to analyze the DNA to determine the planet's original settlers. Spoiler alert: Toward the end of the episode, the analyzed DNA determines both groups shared a common ancestor
Narurally. I think it's widely recognized that social commentary is what distinguishes science fiction (which casts a lens on possible futures extrapolated from our present) from fantasy (escapism, mythology, or hedonism).
well, the first line of the linked page says these are "comic fantasy" and "high fantasy" respectively, so no (though I think Discworld is arguably sci fi). But I get your point and concede that genre boundaries are not solid but more like intersecting clouds.