When judging whether the embryos had edits, He took a few cells from the 200 to 300 present in an IVF embryo and analyzed their DNA. But it was the remaining cells went on to multiply to make up the full body. So it is possible that some parts of the twins’ bodies have edits that He didn’t intend to make (“off-target” edits) and never had a chance to see. Such off-target edits could cause problems such as cancer and heart disease, and could be passed on to Lulu’s and Nana’s future children.

He apparently didn’t realize that his own data revealed extensive mosaicism in the embryos, since he made no note of it in the manuscript I saw. Some have wondered if the CRISPR twins were actually a hoax, but to me, the flaws evident in the data make it clear that they weren’t. Rather, He’s work was a graphic demonstration of attempted gene editing gone awry. Two living human beings, and potentially their descendants too, will bear the consequences.

You shouldn’t have to take my word for any of this. You should be able to judge for yourself, or at least hear what other scientists have to say about it.

However, it seems increasingly unlikely that He will be publishing in a peer-reviewed journal. For one thing, I doubt that any respectable journal would seriously consider publishing research with such ethical problems. And even if one did, and sent the manuscript for peer review, He would be in no position to respond to any technical criticisms with further experimental work. He has been under house arrest, and his laboratory was shut down shortly after his announcement about the twins last year.

The only reason to continue keeping He’s work under wraps would be to preserve his ability to publish it someday in a peer-reviewed journal and earn the imprimatur of scientific quality. The community is under no obligation to grant him this privilege. Indeed, it owes him no professional courtesy at all, any more than it would have owed such courtesy to the doctors responsible for the medical experiments in Nazi Germany or the American scientists in charge of the Tuskegee syphilis study.

Rather, in light of the egregious scientific and ethical lapses inherent in He’s cavalier and secretive efforts to make the world’s first gene-edited babies, it is he who owes all of us a full accounting of his actions. Since he has shirked his responsibility to make his work public, it’s up to others to step in.

Why must the information be public? It’s because He’s work reveals serious, unresolved safety concerns. It’s not clear that any effort to directly edit human embryos, even if done ethically and with full social approval, can reliably avoid these problems.

International committees convened by the World Health Organization, the US National Academies of Medicine and Sciences, and the Royal Society are currently working to propose regulatory frameworks for doing clinical germline gene editing safely, if it is to be done at all. How can the committees properly do their work without fully understanding all the scientific problems with the single real-world application of clinical germline gene editing that’s been attempted to date?

Most worrying is that scientists like Denis Rebrikov in Russia aspire to follow in He’s footsteps. Rebrikov has said he’ll be able to edit the human germline safely. But how can Rebrikov credibly claim to be able to do better than He if the nature of the problems with He’s work aren’t widely known? How can the Russian authorities properly evaluate the safety of his proposals without being able to refer to He’s work for guidance?

It’s time for the scientific community to fully understand what happened with Lulu and Nana, and to avoid stumbling down a path toward further ill-starred experiments with clinical germline gene editing.

Kiran Musunuru is an associate professor of cardiovascular medicine and genetics at the Perelman School of Medicine at the University of Pennsylvania and the author of The CRISPR Generation, a book about the history of gene editing and the Chinese twins.