In May 1999, a disturbing crime shocked the inhabitants of Kollum, a small village in the Netherlands. A local 16-year-old girl was found raped and murdered in a field nearby, and some people said that Iraqi or Afghan residents at an asylum seekers’ centre in the village could be to blame. Tensions rose: a fight broke out at a planning meeting about the centre.

With the case unsolved, the public prosecutor turned to a newly launched research database containing Y-chromosome profiles from men across the world. When forensic scientists compared DNA from semen collected at the crime scene with profiles stored in this Y-chromosome Haplotype Reference Database (YHRD) and elsewhere, they found that the murderer was very probably of northwestern European descent, showing that the villagers’ assumptions were unfounded.

The discovery helped to calm social tensions, although the case was not solved for many years until, with the aid of more DNA work, a local farmer was found guilty.

The YHRD, which was first released online in 2000, is now widely used across the world to help solve sex crimes and settle paternity cases. Holding more than 300,000 anonymous Y-chromosome profiles, it shows how particular genetic markers are fingerprints of male lineages in more than 1,300 distinct global populations.

It can point to the likely geographic origin of mystery males, as in the Kollum case, but is now more often relied on to calculate the weight of evidence against a male suspect whose Y-chromosome DNA profile matches traces found at a crime scene.

Although the YHRD is a research database, scientists both from academia and crime laboratories have uploaded data to it, and it has become a key tool for prosecutors and defence lawyers.

“The YHRD is absolutely essential for suspects anywhere in the world to get a fair chance in court,” says Walther Parson, a forensic geneticist at Innsbruck Medical University in Austria, and the vice-president of the International Society for Forensic Genetics (ISFG).

But some European geneticists say that the YHRD has an ethics problem. Thousands of the profiles it holds were obtained from men who are unlikely to have given free, informed consent, they say. These include data from minority ethnic populations such as the Uyghurs in China and the Roma in eastern Europe.

The criticisms raise questions about consent checks at the YHRD and other databases. They are also the latest strand of a wider campaign to draw attention to a ramping-up of DNA profiling across the world in the absence of stringent ethical oversight.

Some researchers are calling for geneticists to dissociate themselves from this by ensuring that such DNA studies are not given credence by being published in academic journals or databases.

Yves Moreau, a computational biologist at the Catholic University of Leuven in Belgium, has been leading calls for journals and the YHRD to investigate potentially unethical studies. He focuses on China, where the authorities have drawn international condemnation for mass detentions and human-rights abuses in the northwestern Xinjiang province.

Journalists, human-rights groups and academics have collected testimonies from the Uyghurs, a predominantly Muslim population there, of abuses that include the forced collection of DNA. (The Chinese government says it is engaged in a re-education campaign in Xinjiang to quell a terrorist movement.)

“China is pursuing, and trying to export, an authoritarian political model based on surveillance technology, including genetic surveillance of minorities,” says Moreau, who also notes a controversial Chinese effort to build a domestic forensic database by collecting DNA from millions of men across the country. “Researchers, database curators and science publishers should not be complicit in this model — absolutely in no way.”

In part because of Moreau’s work, one set of DNA profiles has been removed from the YHRD, but many more have been questioned. Nature has learnt that the ISFG is now setting up an oversight board to examine cases in which consent is unclear. “Some might think that ethics is merely a lot of annoying bureaucracy,” says Moreau. “But that’s a false perception. Researchers must understand that they won’t get recognition for unethical research.”

Police forces in many nations collect DNA from suspected or convicted criminals, but usually keep this information privately for a limited time (defined by national law) and do not seek consent that would allow it to be shared publicly.

By contrast, public, international DNA research databases that map human genetic diversity contain information acquired from across populations, and require that researchers who upload data have ethics-committee approval and informed consent from participants for their studies.

These databases allow scientists to calculate the frequency with which particular inherited genetic clusters exist in populations, findings that are often useful for medical research.

The YHRD is the largest database to focus on male lineages, and is unusual for its close connection to forensics and crime-solving. It is curated by two forensic geneticists, Sascha Willuweit and Lutz Roewer, who are both at Berlin’s largest research hospital, the Charité.

In common with other databases, it asks for, but doesn’t verify, consent or ethical approval. Researchers who wish to upload data to it are encouraged to first publish an academic paper about their study. which puts the onus on a scientific journal to check for ethical compliance.

In about 10 per cent of cases, says Roewer, scientists have uploaded data without publishing a paper about their work.

In March 2019, Moreau began looking into studies of minority populations in China. He spotted a 2017 review of almost 38,000 Y-chromosome profiles of men in China, held in the YHRD. It was co-authored by Willuweit and Roewer. other authors included researchers from Chinese public-security and police forces.

“I realised that the YHRD was a problem,” says Moreau. The review stated that the profiles had been collected with informed consent, but Moreau argues that it’s hard to see how Uyghurs and other persecuted minority groups could have freely given it.

Moreau went on to find dozens of articles in leading international forensics journals, co-authored by members of the Chinese police, that described DNA profiling of Tibetans, Uyghurs and other minority groups. Most of these papers were not related to the YHRD. He contacted Springer Nature, which publishes some of the journals, and it began to investigate. Note that Nature’s news team is editorially independent of its publisher.

In December 2019, Moreau published his concerns in an opinion article without mentioning the YHRD. Then, in January 2020, he asked the Charité to investigate. It declined, saying that it hosted but did not own or operate the database, a stance it has reiterated to Nature. Moreau began discussing his concerns with Roewer and Willuweit.

Roewer says he agrees with Moreau that researchers shouldn’t be using DNA taken without informed consent, but says that it is not the YHRD’s job to check or to initiate investigations. “We are not an ethical control body,” he says. He also says that, because the 2017 study was a review of already-collated data, it didn’t need ethics approval.

• A Nature magazine report