What race is Meghan Markle? The world has seemed obsessed with the question.

The Royal wedding commentary returned to it time and again, as the bride was referred to as "mixed race" or "biracial".

One British commentator part of ABC's coverage, even wondered ridiculously about the future children of Meghan and Harry who, in her words, could be "all sorts of colours".

Race does not exist

Race is a strange subject. It is an utterly discredited notion; scientists know it is nonsense to even speak of race.

Stan Grant has Indigenous heritage on his maternal and paternal sides. ( Supplied: Kathy Luu )

We belong to one human family, and advances in the study of DNA show we all draw our heritage from different parts of the globe.

In this way, we are all "mixed" race.

As geneticist David Reich says in his recent book Who We Are and How We Got Here, "the genome revolution — turbo charged by ancient DNA — has revealed that human populations are related to each other in ways that no one expected".

Reich says "if we trace back our lineages far enough into the past, we reach a point where everyone descends from the same ancestor …" The evidence of human remains tells us that ancestral "Eve" was from Africa.

Yes, the Queen is an African and Harry and Meghan — like the rest of us — are distant cousins.

Meghan Markle was no more "mixed race" than anyone else at her wedding.

Race has us trapped

Scientifically, race is rubbish: yet, it matters. It matters because as a society we have made it matter.

Ideas of "race" have brought out the worst of humanity.

They have inspired — and continue to inspire — genocide, holocaust, war, dispossession, colonisation, imperialism, slavery, lynchings, segregation, mass incarceration.

Personally and individually it ties us in knots.

Meghan Markle's mother is considered black and her father white.

Until very recently, America's "one drop" rule — one drop of "black blood" — made the Duchess "too black".

The American census now allows people to self-identify in ever-more convoluted and exotic abstractions and hyphens.

The golfer Tiger Woods has gone to ludicrous lengths to describe himself, inventing his own category "Cablinasian" to reflect his Caucasian, Black, Indian, Asian roots.

Meghan herself, in an op-ed for Elle magazine, wrote of how she has embraced "the grey area surrounding my self-identification, keeping me with a foot on both sides of the fence".

Race has us trapped.

It is all but impossible for us to think about ourselves or articulate a sense of identity without referring to race.

More than a check-box

I identify as an Indigenous Australian — there is deep indigenous heritage in my mother's and father's families.

Historically, we have been categorised as "Aboriginal" or "Indigenous", or more colloquially or disparagingly as "blacks".

Barack Obama made history as the first black president of the United States. ( Jason Reed: Reuters )

That has meant at various times being subject to government policy that has restricted our liberty; has told us where we could live and who we could marry.

Families have been divided on arbitrary rulings of colour.

The Australian Law Reform Commission lists historically more than 60 different definitions of who was considered as Indigenous.

Today, I am asked to tick a box on the census form identifying whether I am Aboriginal. It is an entirely invented category that erases the complexity of my heritage.

I am descended from Wiradjuri and Kamilaroi people but I also have an Irish convict ancestor and my maternal grandmother was European.

How can that census box possibly contain all of me?

See how quickly we become bogged in the swamp of scientifically meaningless racial categorisation: was my grandmother "white"? My grandfather black? Are both of my parents "biracial"?

Genetically, none of us are "pure". "Whiteness" is often normalised and "blackness" seen as something "other". These are relationships of power not science.

Can we be truly post-racial?

This was the tantalising possibility raised by the election in 2008 of Barack Obama as America's president, a man with a white mother and a black Kenyan father.

His election was hailed as the fulfilment of the Martin Luther King Jnr promise of being judged not by colour but character.

The writer Toure challenged the whole idea of "blackness" in his book Who's Afraid of Post-Blackness?

He said "the point of fighting for freedom is for black folk to define blackness as we see fit".

As he made clear, there are forty million blacks in America and forty million ways to be black.

Historian and social scientist David Hollinger has called for Americans to "push yet harder against the authority that shape and colour have historically been allowed by society to exert over our culture".

Hollinger, in his book Post-ethnic America, dismisses the idea of "fixed" identities, he favours making room for new communities that promotes solidarity between people beyond definitions of race or ethnicity.

As he says we "live in an age not of identities but affiliations".

It is a worthy idea that remains a work in progress.

Obama spoke of a "nation where all things are possible", yet, as historian Garry Gerstle points out:

"If Obama's election produced spasms of racial vertigo, the reality for millions of African-Americans who cheered his victory, continued to be contoured by the very forces of racial segregation, police brutality, poverty, unemployment that in some quarters, Obama's election had suddenly made irrelevant".

Race matters, even if the evidence tells us it should not.

Shifting our language is not some kumbuya, all-hold-hands fantasy — it is urgent: race exacts a terrible human toll.

Reverend Michael Curry gave a powerful wedding speech about the transformative power of love. ( AP: Owen Humphreys )

Race the new witchcraft

Historian, Barbara Fields and her sister, sociologist Karen Fields, remind us that "race is the principle unit and core concept of racism".

Racism, they write, is a social practice that "always takes for granted the objective reality of race".

Race is voodoo; it is no different, they argue, than witchcraft. In their book Racecraft, they point out that:

"Neither witch nor pure race has a material existence. Both are products of thought and of language."

Witchcraft they say only exists when people "act on the reality of the imagined thing". It is the action that creates the evidence.

There is nothing in the hue of a person's skin that creates segregation and suffering; it happens when people act on ideas about that skin colour.

The Fields sisters say we have moved beyond fears of witchcraft, but "racecraft" persists.

They reject the language of race, even terms like "mixed-race" or "post-racialism", which draw from the same well as racism.

A better way to approach Markle

That's what all the discussion about Meghan Markle's "race" was really doing — perpetuating voodoo science and fuelling the same old fears of difference, as if that has not done enough damage to our world already.

How much better to celebrate that wonderful cosmopolitan meeting of cultures, sharing the joy of Harry and Meghan, and reflecting on Bishop Michael Curry's message of the transforming power of love than the discredited notions of race ands colour.

Matter of Fact with Stan Grant is on the ABC News Channel at 9pm, Monday to Thursday.