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I hate to break this to you,Ìýbut every child is a genetic experiment – and natureÌýdoesn’tÌýcare if things go wrong. Our genomes are awful messes created by conflicting evolutionary forces, and every one of us is a new throw of the genetic dice, with a hundred or so brand–new random mutations thrown into the mix.Ìý

For this reason, I have no doubt that if civilisation survives the various looming crises – including but not limited to climate change – gene-editing embryos will one day become routine. Eventually, natural conception could even come to be regarded as irresponsible.Ìý

We’veÌýan awfully longÌýway to go before we get to that point – although you would be forgiven for thinking otherwise, ifÌýyou’veÌýbeen listening to tech-broÌýhypeÌýthis year. In 2025, we learned ofÌýno fewer thanÌýthree start-ups that are aiming to create gene-edited babies.

So, are CRISPR babies just around the corner – or could start-ups like theseÌýactually beÌýcounterproductive?Ìý

Preventing genetic diseaseÌý

Two of the start-ups –ÌýÌýandÌýÌý– have said their aim is to prevent serious inherited diseases rather than enhance people. A worthy aim. But the good news is that such conditions can already be prevented by various screening methods, such as genetic testing of IVF embryos before implantation. There are very few cases where screening will not work.Ìý

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So why would you found a company to develop a technically and legally tricky product – gene-edited embryos – whenÌýthere’sÌýalready an existing product – IVF screening – without these issues?Ìý

When I put this question to the two companies, PreventiveÌýdidn’tÌýreply, but a spokesperson for Manhattan Genomics said that couples undergoing IVF oftenÌýdon’tÌýhave enough embryos to select from. If embryos that carry disease can be edited rather than discarded, this increases the chances of a child being born. The company estimates that gene editing “could correct approximately 10 Huntington’s disease-affected embryos and 35 sickle cell disease-affected embryos each year just for couples currently using IVF”.ÌýÌý

This would equate to a tiny number of children – only around a third of implanted IVF embryos result in a live birth and this is likely to be lower after editing.ÌýWhat’sÌýmore, there are also serious issues with doing this. Firstly, while CRISPR methods have advanced hugely,Ìýthere’sÌýstill a risk of dangerous mutations occurring as a side effect.Ìý

Secondly, the editing process oftenÌýdoesn’tÌýstart or can continue after an embryo begins dividing. That means there will be different changes in different cells within a single embryo – a phenomenon called mosaicismÌýseen in CRISPR children illegally created in ChinaÌýand announced in 2018.Ìý

What this means is that you cannot tell for sure whether a disease-causing mutation has been successfully corrected in an edited embryo, and without any dangerous mutations.ÌýThat’sÌýa showstopper.Ìý

Doing it the right wayÌý

There are potential solutions. For instance, some gene-edited animals are created by altering stem cells and then cloning cells onceÌýyou’reÌýsure they have the desired changes. However, as IÌýdescribed in my previous column, cloned animals have lots of health issues and unexpected physical differences. This is why much more basic research is needed, and why rigorous scrutiny will be hugely important, if this approach is ever tried in humans.Ìý

We now have two excellent examples of how the gene editing of embryos could be responsibly introduced, in the form of the rollout of mitochondrial donation in the UK and Australia. Mitochondria are energy-producing structures in cells that have their own tiny genome. Mutated mitochondria can cause serious diseases if passed on to children, but this can be avoided by replacing them with healthy donor mitochondria.Ìý

A form of the mitochondrial technique was offered by private fertility clinics in the US in the 1990s, resulting in the birth of what I would describe asÌýthe first genetically modified humans. Those early efforts resulted in the technique being banned in the US.Ìý

Mitochondrial donation used to be illegal in the UK,Ìýbut after campaigning by patient groups, and widespread consultation and discussion, theÌýlaw was changedÌýand there is nowÌýcase-by-case approval on a trial basis. Australia isÌý.Ìý

What’sÌýthe real goal?Ìý

This is how new reproductive techniques should be introduced: openly, legally and as part of independently overseen trials.ÌýInstead, at least two of the start-upsÌýÌýdoing experiments in countries where there are fewer laws governing the use of gene editing in embryos.Ìý

ThisÌýwouldn’tÌýadvance the science, as weÌýwouldn’tÌýbe able to trust claims made by private companiesÌýoperatingÌýoutside regulatory oversight. On the contrary, it could lead to a backlash, with more countries introducing or tightening laws against gene editing.ÌýÌý

The truth about de-extinction: is it even possible, and why do it?

Ambitious projects aim to put dire wolves, woolly mammoths and passenger pigeons back into our ecosystems. But with so many technical and ethical hurdles, what is the real motivation?

If billionaires – Preventive’s investors include Sam Altman of OpenAI andÌý, for instance – really care about preventing serious inherited diseases, they would achieve far more by putting the money into non-profit research organisations.Ìý

Or,Ìýrather than helping other couples have healthy kids, is theÌýultimate aimÌýto have enhanced children of one’s own? That is the explicit goal of the third start-up,Ìý.ÌýÌý

So, could we use gene editing to enhance our kids if we wanted?ÌýI’llÌýgive you the answer in my column next month.Ìý