Here are some of the things that people are saying about mixed-race babies at the moment: websites have run stories about the “viral” mixed-race children of Instagram, who are trending because of their “gorgeous blonde hair, light eyes, and golden skin that looks like sand”. White teenagers – in conversations that I have both overheard and been privy to – say, “I really want to have kids with a black guy because mixed-race babies are so cute! I just love their curly hair, and oh my God, the ones with freckles.”

The Kardashians, who have been accused by some people of turning that particular fantasy into reality, are a never-ending source of related commentary. Kylie Jenner is currently causing people to “fall all over themselves with praise” because she learned how to do her mixed-race daughter’s hair.

And now I have had more than 20 requests to do broadcast and print interviews about the impending arrival of Harry and Meghan’s baby – due any day now – on what it means for British identities that this royal baby will be the first to be acknowledged as mixed race.

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I know why I’ve been asked, because this was the theme of my contributions this time last year around their wedding. I gave freely of my view that the fact that a woman who proudly identified with having African heritage was entering the senior echelons of the royal family would make it that much harder for people to claim – as they had in the past – that to be black and to be British were mutually exclusive identities.

But the situation today is completely different. This is the birth of a child. A child who will have to navigate for themselves the madness of all the ways in which we have been taught to essentialise and fetishise race.

Because that’s exactly what this fawning over the attractiveness of mixed-race children on social media boils down to. In the past, the offspring of interracial relationships were regarded with a unique hostility. Marie Stopes may be eulogised for her work on contraception and reproductive rights, but it’s often forgotten that she was motivated in part by eugenicist ideas, including the one that “half-castes” should be “sterilised at birth”.

Oscar Wilde’s depiction of a mixed-race man in The Picture of Dorian Gray is symptomatic of the depravity with which this unnatural species was regarded in the Victorian era – entering an East End opium den, Gray encounters “a half-caste, in a ragged turban and shabby ulster”, who “grinned a hideous greeting”.

It was regarded as an ugly trope then; it’s seen as an attractive one now. Mixed-race people were thought to be mentally subnormal in 1930s England, while today they are viewed as aesthetically blessed. But both instances simply bring out the worst of our tendency to essentialise race and ethnicity, so that mixing is seen as a kind of social test tube for genetic experiments to maximise desirable tendencies in the next generation.

Having multiple heritage is a blessing, but also guarantees that it will be a challenge to make sense of your identity

Not that all the commentary has been gushing. The arrival of Meghan Markle all on its own invented a new media genre of dog-whistle-mixed-race-princess-bashing: the pushy American who has the nerve to put her baby bump front and centre (seriously – where else does one put one’s baby bump?), who has the chutzpah to exercise choice over who delivers her child, and who stubbornly refuses to fit in with royal convention and protocol – rebelling in her manner of opening and closing doors, and her choice of nail polish palette.

But that is also the context into which her child will be born. Having multiple heritage is a blessing, but in many cases it also guarantees that it will be a challenge to make sense of your identity. It means being born in between racial groups whose whole invention was designed to make them oppositional to each other. Whiteness needed blackness to reinforce its superiority. Blackness needed to be inferior to justify enslavement, colonialism and segregation.

Far from shaking off that history, we still use even the words it gave us as our blunt and problematic tool for talking about race. Even the language I’m using right here – “mixed‑race”, as I sometimes describe myself, “biracial”, as Meghan describes herself, “mixed heritage”, “multiple heritage” – all of these words are just remixes of an old vocabulary of “mulatto”, “quadroon”, “half-caste”, and “Métis”, which sought to reinforce the idea that a person enjoyed racial superiority to the extent to which they had white blood.

So what am I supposed to say about the royal baby? The birth of a child is a gift to eclipse all others. To have a family whose heritage straddles the racial divides into which we’ve been socialised is to be born with a bunch of questions that the people around you will struggle to answer. To be born into a family that played a greater role than most in profiting from those divides – as is the case with Britain’s royal family – is unimaginably complicated. From the bottom of my heart, I wish this child well.

But I feel the exact same way about every other child destined to grapple with these questions. And if what the media wants is some kind of racial soothsaying from me on another person’s identity, some analysis of this child’s hair texture, skin colour, the number and significance of its freckles, and what that will mean for the future of the monarchy, I’m afraid you’re not getting that from me.

• Afua Hirsch is a Guardian columnist