What in that link was relevant to your point?
An ethnic group is a group of human beings whose members identify with each other, usually on a presumed or real common heritage.[1][2] Ethnic identity is further marked by the recognition from others of a group's distinctiveness[3] and the recognition of common cultural, linguistic, religious, behavioral or biological traits,[1][4] real or presumed, as indicators of contrast to other groups.[5]
Ethnicity is an important means through which people can identify themselves. According to "Challenges of Measuring an Ethnic World: Science, politics, and reality", a conference organized by Statistics Canada and the United States Census Bureau (April 1-3, 1992),
"Ethnicity is a fundamental factor in human life: it is a phenomenon inherent in human experience."[6]
There are no race specific traits. There are traits that are more common within certain populations.
Predominance is in itslef a trait.
African populations can exhibit light skin (albinism)
That is a mutation, it is a genetic anomally, let's leave it to non-anomolous passing of genes shall we.
straight hair and thin noses (Somali's) and epicanthic folds (Khosian).
Different region, different people, but I see your point.
Once again all these traits are clinal and gradually change.
Yes, they change because of the nature of reproduction and genetic inheritance itself, that gets complicated and involves centuries of ancestory, but it doesn't disprove that different people have different traits, some are more prominent among various ethnicities(race)
Any cut-off point where we declare skin to become white, noses thin, hair straight etc. are simply arbitrary.
Not when they are predominant traits
Monotype specifically means that no races exist. Beyond basic DNA structure we are all different.
That would be like saying a Sheppard is a Collie is Retriever, they are all dogs, they can all breed together, but they aren't all the same now are they?
Rather there is more variation within a population than between them, two Europeans are less genetically similar than a European and African.[
But may not share the same traits.