Why Does the Left Insist that Race is a Social Construction?

I just got through Ron Unz's review of "White Racialism in America, Then and Now." A large part of his article related to the fact that you are not allowed to say or write that race is real and has an impact on IQ.

I wonder why?

Is it because the left's power depends on the notion that everything especially intelligence, is culture driven, and therefore malleable by education and therefore by a wise and educated and evolved elite?

I had a discussion with a liberal friend about this. She said that race was a social construction, and I said so why does 23andme.com purport to be able to tell your ethnic origin by testing your genes? 

In other words, if we said that humans are what they are, mostly defined by their genes, and then by their peers, and then by their parents, could there be an intellectual foundation for the current religious doctrine of All Power to the Educated Gentry? Or should we just give up on the progressive project and let people be who they are.

By the way, some researchers have done research that says that a population's IQ goes up as they become more prosperous, or, I imagine, integrated into the modern market economy.

But you have to wonder. What does it mean when an idea is so scandalous that you are not allowed to hold it and publish it? Obviously, I would say, it says more about the cancelers than the canceled.

What I wonder is: how much does it really matter if blacks have a lower IQ than the average white American? For instance, I have read recently that East Asian Americans have a higher average IQ than Jews. And, as we know, American Jews have a higher average IQ than white Americans. But does it matter?

Suppose it does matter. Does it matter enough that any discussion of IQ by race is forbidden and anyone that publishes an argument that IQs really do vary by race should be canceled? Does it matter enough to cancel the heretics?

I get the notion that there is a political dimension to this, that educated Gentry power to some extent depends on the right of the Gentry to order us all around, and this is helped by assuming that race is a social construction.

But why does this practical consideration get elevated into Holy Writ? Nobody expects the Spanish Inquisition.

OK, I get the need to rile up blacks at election time, because without blacks voting 90% Democrat, Democrats lose power.

I get the need to insist that the argument for equality -- and the need for educated Gentry power -- depends on all humans being alike and all differences in outcome the result of oppression and exploitation.

I get that for small minorities like Jews and blacks, there is a need for unity, and a corresponding need to divide the majority.

Wait: I would say that for the leaders of small minorities there is a need to flog the members of the minority community into unity and the way to do this is to create a culture of danger, of possible attack by the majority culture. Therefore the leaders of the minority should be strive to maintain a culture of unity; therefore it doesn't hurt to try and divide the majority.

But I wonder why, say, Jews are still organized in a culture of unity and innocence after a century in the US. And why blacks have a culture of unity 50 years after the Civil Rights Acts of the 1960s.

All this, to me, is matter of fact and by the way.

I still don't really understand why the issue of race and IQ has to be radioactive. I suspect that I am missing something, but I don't know what it is.