For a few, signing up with DNA-testing outfit 23andMe proved a life-changing experience: reuniting them with long-lost siblings or revealing relatives they never knew they had. Sometimes, the discoveries were no less seismic but not quite so welcome – one family learned that the daughter they’d raised for 18 years wasn’t actually their biological child thanks to an embryo mix-up at a fertility clinic.

But even they would have to concede they’d learned something fundamentally new about themselves, which was always the main promise of the ground-breaking ancestry tracing company named after the 23 pairs of chromosomes that make up each human cell.

And for millions more who paid for the testing kits out of idle curiosity, there was not only the chance to learn just a little more about their origins but possibly to identify genetic health conditions in time to do something about them.

Just three years ago, 23andMe was being hailed as Silicon Valley’s latest golden success story, with 15million subscribers and a share price higher than Apple’s.

Celebrities and billionaires, including media magnate Rupert Murdoch and the now disgraced Hollywood mogul Harvey Weinstein, thronged glitzy ‘spit parties’ to promote 23andMe, whose Personal Genome Service – its flagship product – was named Time magazine’s Invention of the Year in 2008.

Meanwhile, around seven per cent – or 4.7million – of the British population is estimated to have used a DNA-testing kit, encouraged by the popularity of ITV series DNA Journey, which traced the ancestry of pairings including Ant and Dec, sportsmen Freddie Flintoff and Jamie Redknapp, and entertainers Amanda Holden and Alan Carr.

All you have to do after buying a 23andMe home-testing kit – currently on offer at the heavily-discounted price of £59 – is spit into a tube and send it back to 23andMe in a box with a prepaid return label. And then just wait a few weeks to discover what the wonders of DNA analysis can reveal about your ancestry.

Now, however, in a stunning fall from grace, the US-based company once hailed as ‘the future of medicine’ and valued at $6billion (£4.8billion) is on the verge of bankruptcy.

Despite chief executive Anne Wojcicki’s insistence that she ‘plans’ to take the business private, speculation is rife that she will either have to sell it off or the company will simply fold

Just three years ago, 23andMe was being hailed as Silicon Valley’s latest success story, with 15million subscribers and a share price higher than Apple’s

Its share price has plummeted and a few weeks ago it was almost de-listed from America’s Nasdaq stock market. Last week, it announced it is laying off around 40 per cent of its workforce and closing its drug development arm. The board resigned in the summer, leaving only its chief executive and co-founder Anne Wojcicki in office.

For all its supposed brilliance and hype, 23andMe’s business model was dismissed as fundamentally flawed. After all, once they’d paid for their DNA report, there was little incentive for customers to stump up for more information.

Despite Wojcicki’s insistence that she ‘plans’ to take the business private, speculation is rife that she will either have to sell it off or the company will simply fold.

That strong possibility has triggered growing alarm over the fate of the firm’s biggest asset: its treasure trove of hugely sensitive but enormously valuable personal data.

23andMe doesn’t just have the genetic data of its 15million customers, but also of their parents, siblings, children and even distant relatives – who share much of their DNA – despite not giving their consent for the company to obtain it. (Research indicates that 90 per cent of white Americans can be identified on genealogy websites even if they’ve never submitted their own DNA.)

And unlike other personal details we share on the internet such as email addresses, bank account codes and telephone numbers, genetic data cannot be changed.

In fact, the implications of genetic data breaches are, says University of California law professor Nila Bala, ‘staggering’ and carry ‘profound risks’.

She and other experts warn that sensitive information about health and someone’s genetic susceptibility to certain illnesses can lead to discrimination in schools, housing and insurance.

Some 4.7million Britons have used a DNA-testing kit, encouraged by the popularity of ITV series DNA Journey, which traced the ancestry of celebrities including Ant and Dec

University of California law professor Nila Bala says the implications of genetic data breaches are ‘staggering’ and carry ‘profound risks’

‘Your DNA can reveal a tremendous amount about your health and future health,’ Suzanne Bernstein, legal counsel at the Electronic Privacy Information Centre in Washington DC, told the Mail. ‘And that information ending up in the hands of anyone is not what you expected when you signed up with 23andMe.’

It surely won’t be news to anyone who uses the internet that everything they do and reveal online is being systematically swept up and sold to advertisers and other private companies, in what’s nowadays called the ‘commercial surveillance ecosystem’, so they can more effectively target potential customers for their products and services.

DNA information, however, opens up frankly terrifying new vistas of potential misuse. It could even be used to create biological weaponry: the genetic information allowing deadly pathogens to be targeted not only at specific battlefield opponents but potentially at an entire enemy population.

Some Western analysts say China has been hoovering up huge DNA troves around the world for years with a view to creating just such genetic-based weapons. One of the principal ways it’s been doing it, say intelligence officials, is by buying US genetics companies or hacking them.

US House of Representatives intelligence committee member Jason Crow warned two years ago that Americans shouldn’t be complacent about sharing their genetic information with private DNA-testing companies – such as 23andMe – for precisely this reason.

And yet experts say people aren’t entirely to blame for over-sharing online, as companies intentionally make it immensely hard for customers to find out what they might do with their personal information. They compose lengthy privacy policies stuffed with unintelligible legalese that are specifically designed to deter punters from wading through them.

If you can find it, the privacy policy of 23andMe says that if the company is sold, a user’s personal information can be transferred to the new entity as part of the deal.

The UK and Europe admittedly have stronger data protection laws than the US when it comes to covering what happens to private information if a company goes bankrupt or changes hands.

Google – whose co-founder Sergey Brin was married to 23andMe boss Wojcicki (both pictured) – poured millions into the new venture in 2007.  Critics say Google has a terrible track record for respecting users’ private information

However, the toughest regulations are no protection when companies are hacked, which is exactly what happened to 23andMe last year.

The data watchdogs of both the UK and Canada have launched an investigation into how hackers gained access to the personal information of 6.9million people by using customers’ old passwords. The stolen data didn’t include DNA records but it still raised fears that 23andMe isn’t doing enough to safeguard data, while the theft contributed significantly to the company’s worsening reputation.

The spectacular rise and fall of 23andMe is a cautionary tale that tells us much about the parlous state of privacy in the digital world and the risks of consigning our most personal information to an industry that has an abysmal track record for protecting it.

Some critics have long been sceptical about 23andMe, claiming its real goal has always been to hoard personal data. These doubters certainly smelled a rat after Google – whose billionaire co-founder Sergey Brin was married to 23andMe boss Wojcicki when she helped set up the company – poured millions into the new venture in 2007.

Google, along with other Silicon Valley giants, they noted, had a terrible track record for respecting users’ private information.

In 2021, 23andMe merged with a company owned by Richard Branson’s Virgin Group eight months before being listed on the stock market.

Once the darling of DNA-testing, the company may yet weather the storm – although few people are confident that will happen.

Meanwhile, another such company, Atlas Biomed, which has offices in London but apparent links to Russia, has abruptly ceased trading without informing customers what has happened to their private information. They are naturally very worried.

And given the likely fate of 23andMe, they most certainly won’t be the last.