Genetically similar to what extent? Why not make all red haired people into a race? They're more similar to one another than non-red haired, but fair skinned, people. More importantly, why is the current classification any less silly than my redheads example?
I feel that Dalamon would make his points better understood if he used a simpler style. He is not doubting that phenotypes exist. Like duh!
However, group phenotypes are AVERAGE. For example, Germans are on average lighter skinned than the Chinese. But that's not always the case. I've seen many Chinese who are lighter skinned than many Germans. Similarly, more Irish people have blue eyes than Greek people. But I've met Greeks with blue eyes, and Irish with brown eyes. However, phenotypes can be useful. If I learn than someone is from a Congolese or Norwegian or whatever ethnicity, I'd picture a certain look. I'd likely to get at least some of it right.
But race is a genetically arbitrary GROUPING of phenotypes. It only exists because we said it is so. If everyone's memory is wiped out overnight (and people were scrambled randomly across the planet), the concept of race wouldn't develop the same way it is now, if it developed at all. The historical circumstances behind its development would not exist, and others would take their place. That is not the case with natural distinctions between humans. Even with wiped memories, we would still recognize that some people are shorter, others taller. Some are lighter while others darker. Some have blond hair while others have black hair. But the racial groupings would change. Middle Eastern people might be grouped with Indians or Baltic people or Southern Europeans or Latin Americans. Sri Lankans might be grouped with Sub-Saharan Africans. And so on.
So ya, race is a cultural phenomenon, and one that I find useless and would rather do without.