When British teenager Shamima Begum’s citizenship was revoked last February, the then home secretary, Sajid Javid, justified the response in the name of protecting national security. Married to an Islamic State militant eight years her senior and heavily pregnant with their third child at the time, it was difficult for many people to sympathise with Begum – who had left Britain in 2015 aged 15, along with two schoolfriends, to join Isis in Syria.

She had further dismayed the public when, in her first interview after being discovered in a refugee camp, she remarked nonchalantly, “When I saw my first severed head it didn’t faze me at all.”

Given that all ethnic minorities have family connections to other countries, it now places a question mark over all of our futures

Today, at the Special Immigration Appeals Commission, Begum lost her appeal challenging the home secretary’s decision. The ruling will no doubt be popular – it’s difficult to have much sympathy with anyone who willingly signs up to the virulent misogyny and bloodlust of Isis. However, Begum’s banishment throws up two major questions.

First, we need to know why a straight-A teenager from east London would willingly leave Britain to embrace a death cult. It defies all reason. Somehow this child was groomed and radicalised, not in some far-away country bereft of democracy, but here on British soil and without the knowledge of her parents. Before condemning her we need to know how this naive teenager was pushed in this direction. If she’d been sexually groomed at this age we would not be vilifying the victim.

And, second, the British government’s decision to sever her citizenship is in effect burying its head in the sand. Though Bangladesh has washed its hands of her, Javid, and his successor Priti Patel, still claim Begum can apply for citizenship in that country, where her parents were born. But she’s a product of Britain, not of Bangladesh – a country she has never visited. Her rights as a British citizen – born here, raised here, and with an east London accent – should transcend the seriousness of her crime, and she should be tried on British soil. Doing otherwise sets a dangerous precedent.

And, moreover, it sends a signal to all British ethnic minorities. Like many of us born here in families whose parents or grandparents migrated from abroad, Begum knows this country and no other. And until recently it’s only been the far right who have questioned black and brown people’s right to be here. But given that all ethnic minorities have family connections to other countries, it now places a question mark over all of our futures. Should we be convicted of a crime (and let’s face it, our communities are already heavily policed and there’s a long history of us being unfairly targeted by the criminal justice system), we may now face a double punishment – of deportation as well as the original sentencing.

As a British citizen myself, of Pakistani descent, is it fair that my citizenship rights could be stripped if I committed a crime, that I could be banished to a country where I have no tangible connections other than the fact my grandparents migrated from there decades ago?

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More and more, the idea of “Britishness” seems to be squeezing out ethnic minorities, and especially our right to be who we are. We’ve had a decade of attacks on multiculturalism; endless debate about “British values”, including a test announced by Javid in 2016; we’ve seen a rise in hate crimes since the Brexit referendum. And to cap it all, we’ve had the Windrush scandal, and the election as prime minister of a man who insults Muslim women and black people. A British identity inclusive of black, Asian and minority-ethnic communities is dying right before our eyes.

When I was growing up, my grandparents who migrated from Pakistan to the UK in the 1960s – when the far right National Front loomed daily – spoke ominously of returning to Pakistan before the British government kicked them out. They were the generation who shuddered as they listened to Enoch Powell lament that “in this country in 15 or 20 years time the black man will have the whip hand over the white man”.

Begum’s crime (for which she has yet to be tried) is grievous indeed. However, with this verdict upheld, the government message is loud and clear: play by the rules, or risk having your citizenship revoked. It seems my grandparents weren’t as melodramatic as I thought after all.

• Aina Khan is a writer and playwright and a former presenter for British Muslim TV