[cygx]

Some ethnicities are more susceptible to certain diseases. Is that a social construct?

Obviously not. But quoting Wikipedia[1], an average of 85% of genetic variation exists within local populations, ~7% is between local populations within the same continent, and ~8% of variation occurs between large groups living on different continents, whereas [a]pproximately 10% of the variance in skin color occurs within groups, and ~90% occurs between groups, which indicates that this attribute has been under strong selective pressure.

When defining human race, we hone in on a few easily identifiable characteristics that have remained stable due to selective pressure (eg skin colour) and overblow their significance. Eg we suspect that humanity went through a genetic bottleneck when it left Africa, decreasing diversity. And yet, we generally lump the rather diverse African population that did not go through it into a single race.

It's probably more useful to just look at specific genetic traits of interest instead of drawing somewhat arbitrary boundaries.

[1] https://en.wikipedia.org/wiki/Human_genetic_variation

[fdsaaf]

> 85% of genetic variation exists within local populations

That's Lewontin's Fallacy [1]. There's no logical reason to think that genome-wide diversity within populations somehow proves that large-scale impactful allele frequency differences between conventionally understood races do not exist.

They do. You can measure them. Given someone's DNA, you can identify his content-scale race. (You can actually narrow someone's ancestry much more narrowly too. Race is a cakewalk.)

[1]:

http://onlinelibrary.wiley.com/doi/10.1002/bies.10315/abstra...

"In popular articles that play down the genetical differences among human populations, it is often stated that about 85% of the total genetical variation is due to individual differences within populations and only 15% to differences between populations or ethnic groups. It has therefore been proposed that the division of Homo sapiens into these groups is not justified by the genetic data. This conclusion, due to R.C. Lewontin in 1972, is unwarranted because the argument ignores the fact that most of the information that distinguishes populations is hidden in the correlation structure of the data and not simply in the variation of the individual factors. The underlying logic, which was discussed in the early years of the last century, is here discussed using a simple genetical example."

[notahacker]

There is also no logical reason to believe that allele frequency differences betwen conventionally understood races are in any way "impactful" relative to the heterogenity of respective groups or relative to allele frequency differences between populations not generally understood as distinct races.

We can reliably identify haplogroups associated with certain phenotypes popularly categorised as "races", but we can also [more] reliably identify genetic markers associated with other phenotypical differences which have little or no correspondence with haplogroups. The presumption of greater significance of haplogroup-associated differences is the social construct here.