[Amezarak]

No, I have no problem with OP's arbitrary lines - they are meaningful even though reality necessitates any such lines of this type (categorizing individuals) be drawn arbitrarily. What I have a problem with is people moralizing about science - we shouldn't even think about things because they make you uncomfortable.

There is an is-ought distinction. We can reason, investigate, and speculate about the ancient Roman people and their distinctiveness and what populations today have the closest genetic distance without there being any implication whatsoever socially or legally.