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In November 2018, Chinese scientist He Jiankui announced the birth of the first genetically modified children — twins whose DNA he edited at the embryo stage. The world reacted with shock. He was sentenced to three years in prison. But the technology did not disappear. It has become more precise, more affordable, and is already being used in clinics. Just not to create «enhanced» children — for now it is used to treat hereditary diseases.
I decided to get to the bottom of this: where is the line currently drawn between therapy and human engineering? What is technically possible, what is permitted by law, and what do the geneticists themselves — those who work with CRISPR every day — think?
How embryo genome editing works
Let's start with the mechanics. CRISPR-Cas9 works like molecular scissors guided by a navigator. You program the system to search for a specific DNA sequence — for example, a gene with a mutation that causes cystic fibrosis. The Cas9 enzyme cuts that sequence. Then the cell repairs the break, and you can provide the correct version of the gene as a repair template.
It sounds simple. In practice there are many nuances. I spoke with Karina Schmidt, a geneticist at the Institute of Molecular Biology in Munich. She explained:
«The problem isn't cutting DNA. The problem is accuracy: CRISPR can miss the target and edit a similar sequence elsewhere in the genome — an off-target effect. In adult somatic cells this is a risk that can be managed. In an embryo, however, the change can be present in all of the organism's cells and may be passed on to subsequent generations».
That is precisely why embryo editing is banned or strictly limited in most countries. In Germany it has been completely prohibited by the Embryo Protection Act since 1990. In the U.S., federal funds cannot be used for such research. In the UK, research is allowed only on embryos up to 14 days of development — and those embryos cannot be implanted.
But there is a gray area. Some countries do not regulate this field at all. Others formally ban it but do not effectively control private clinics.
What is already being done in clinics right now
Pre-implantation genetic diagnosis (PGD) has been used in reproductive medicine clinics for two decades. The procedure is straightforward: during IVF, several embryos are created, one or two cells are taken from each embryo, and the DNA is analyzed. An embryo without the targeted genetic disease is selected for implantation.
This is not genome editing. This is selection. The result can be similar: a child is born without the hereditary disease the parents carry.
I asked Karina which diseases are screened for most often:
«Monogenic diseases with a known mutation: cystic fibrosis, sickle cell anemia, Duchenne muscular dystrophy, Huntington's disease. If both parents are carriers of a recessive gene, the probability of an affected child is 25 percent. PGD reduces that risk to zero. This isn't eugenics. This is the prevention of suffering».
But the technology allows for more. You can screen an embryo for predisposition to conditions such as diabetes, certain cancers, and Alzheimer's disease. You can select sex — in some countries this is legal for medical reasons, in others it is banned. You can check tissue compatibility if the family already has a sick child who needs a bone marrow donor.
The last case is particularly illustrative. In 2000, Adam Nash was born in the U.S. — the first «savior sibling». His embryo was selected based on two criteria: the absence of Fanconi anemia and compatibility with his sick sister. Cells from his umbilical cord blood were used for transplantation. The girl recovered. Adam is now 24, healthy, and — judging from interviews — does not regret his birth.
Is this medicine or the instrumentalization of a human being? The question remains open. But the fact is: the technology works and is being used.
The difference between treatment and enhancement
The line looks obvious on paper. Treatment is the elimination of disease. Enhancement is the alteration of normal traits toward desired ones. In reality, everything is more complicated.
Take height. Achondroplasia is a hereditary disorder that leads to short stature; the average adult height with this diagnosis is about 130 centimeters. Is this a disease or a variation of the norm? Many people with achondroplasia live full lives and do not consider themselves sick. At the same time, they have an increased risk of spinal and respiratory problems and face everyday limitations.
If you edit the FGFR3 gene in an embryo — is that treatment or a cosmetic modification?
Now another example. The PCSK9 gene helps control cholesterol levels. People with a natural mutation that inactivates this gene have very low cholesterol and an approximately 88 percent lower risk of cardiovascular disease. No adverse effects have been identified. If you introduce such a mutation into an embryo — is that prevention or enhancement?
Karina proposes one practical criterion:
«The line is where suffering ends. If a child without intervention would be born with a disease that shortens life or makes life agonizing — that is an indication for therapy. Everything else is enhancement, even if it's beneficial».
But this is a philosophical position, not a legal standard. Laws differ between countries. In the UK it is permitted to select embryos that do not carry a BRCA1 mutation, which can raise lifetime breast cancer risk to around 80 percent. In Germany this is banned — the law allows PGD only for «severe hereditary diseases», and a predisposition to cancer is not considered such.
Technical limitations of editing
Let's assume ethics and laws are not a problem. What can be changed technically right now?
Clearly monogenic conditions — those caused by a single gene — are relatively simple to target. Examples include sickle cell anemia and certain inherited forms of deafness or metabolic disorders. In laboratory settings CRISPR can address these with efficiencies often quoted in the range of 70–90 percent.
The problem is that many traits of interest are polygenic. Height depends on hundreds of genes. Intelligence involves thousands of genes plus epigenetic and environmental factors. Even traits like skin tone are determined by multiple genes with varying contributions.
I asked Karina whether it is theoretically possible to edit all these genes at once:
«Technically, yes, but it's like playing chess blindfolded on a hundred boards at the same time. Genes interact with each other; changing one can unpredictably affect others. There's pleiotropy — one gene influencing several traits. For example, a gene that increases muscle mass might also raise diabetes risk. We simply don't know all these interactions».
There is also mosaicism. When you edit an embryo at the single-cell stage, the change must be copied into all subsequent cells. Sometimes editing doesn't happen immediately, and the organism becomes a mosaic — part of the cells carry the edit, part do not. With the Chinese twins, this is what occurred: analysis showed the modification did not affect all cells uniformly.
The third problem is inheritance. Changes introduced into an embryo's germline will be passed to children, grandchildren, and further generations. If, decades later, a modification proves to have delayed adverse effects, it may be impossible to reverse. This is a genetic legacy across generations.
What animal studies say
Genetically modified mice, pigs, and monkeys are routine in biotech labs. The results are simultaneously encouraging and cautionary.
In 2017 Chinese scientists edited the myostatin gene in Beagle dogs. Myostatin limits muscle growth; dogs with a deactivated gene were roughly twice as muscular as controls without training or special diets. No immediate side effects were reported. The technology is potentially applicable to humans — similar natural mutations are found in some animals and, rarely, in humans.
In 2018 researchers at the Salk Institute produced mice with alterations in the BMAL1 gene, linked to aging. The modified mice lived about 20 percent longer and retained physical activity into old age. It sounds like a victory over aging. But detailed analysis revealed metabolic disorders in some mice and infertility in others.
The most controversial experiment was conducted in 2019 with macaques. Chinese researchers introduced the human version of the MCPH1 gene, implicated in brain development, into monkeys. The animals showed improved performance on certain memory tests. The study provoked international condemnation — not solely for technical reasons, but for ethics. Creating animals with human-like cognitive traits raises profound questions science is not yet ready to answer conclusively.
The economics of genetic modification
Currently, one IVF cycle with PGD in Germany costs between 15,000 and 20,000 euros. Genetic diagnosis accounts for roughly 5,000 euros of that — analysis for known mutations, which is a proven service.
Embryo editing with CRISPR for research purposes costs an order of magnitude more. Expert estimates suggest a commercial reproductive editing procedure — if it were legal — could cost on the order of 100,000–200,000 euros. For comparison, the average salary in Germany is about 50,000 euros per year.
This means the technology would initially be available only to the wealthy. Karina explains:
«This is the main argument against legalizing enhancement. If only children from affluent families can edit their genomes, we'll cement biological inequality across generations. Not a metaphorical elite, but a literal one — people with improved health, longevity, possibly cognitive advantages. This is no longer social stratification; it is the creation of biological classes».
A counterargument is that medical technologies are expensive at first and become cheaper over time. Antibiotics in the 1940s were extremely expensive; now they are widely available. IVF in the 1980s was limited to a few clinics; today it is routine and partially covered by insurance.
Genetic modification differs from antibiotics. It's not the treatment of a single person; it's a change to a lineage. If wealthy families improve their children's genomes and poor families do not, the gap may widen with each generation — not due to education or healthcare, but due to biological differences.
Legal regulation around the world
I compiled a map of legislation for countries where active genetic research is conducted:
Germany: A near-complete ban on embryo editing, including for research. PGD is allowed only for severe hereditary diseases. Violation can lead to criminal penalties.
UK: Research on embryos up to 14 days of development is allowed with a license. Implantation of edited embryos is prohibited.
USA: No single federal law explicitly bans embryo editing, but regulatory and funding barriers exist: the FDA will not approve clinical trials of germline modification, and the NIH does not fund such research. Private clinics could theoretically attempt procedures, but there are no precedents.
China: After the He Jiankui scandal, strict rules were introduced. Embryo editing for reproductive purposes is banned; research is permitted with ethics committee approval. In practice, oversight can be uneven.
Japan: Research on embryos is allowed, but edited embryos cannot be implanted. Rules for human-animal chimera research were relaxed in 2019 with strict conditions.
Russia: No special law on genome editing exists. PGD is allowed. Genetic research falls under general biomedical legislation, which leaves some wording vague.
General trend: most countries permit research but ban the creation of genetically modified children. The problem is that the technology does not require massive infrastructure. CRISPR kits can be ordered for a few thousand dollars. A reproductive clinic with a molecular biologist technically has the capability to perform edits.
Geneticists' opinions on the technology's future
I polled several specialists in Munich and online about prospects for embryo editing. Responses fell into three camps.
Conservatives argue the line must be absolute: no embryo editing, even to treat severe diseases — there are alternatives like PGD. One geneticist from Berlin told me:
«We can create ten embryos and choose the healthy one. Why edit one? The risks of editing greatly exceed the benefits. This is not treating a child; it is making the child a test subject in an experiment.»
Pragmatists allow editing in exceptional cases: for instance, when both parents carry the same recessive mutation so all their children would be affected, or for mitochondrial diseases passed only via the maternal line, which standard PGD cannot address. Karina belongs to this camp:
«The technology must be available where there is no alternative. But it should operate under an international registry, strict oversight, and long-term follow-up. Each case should be treated as a documented scientific study, not a commercial service.»
Liberals believe bans are ineffective and that demand will grow. Better to legalize and regulate. One researcher from Switzerland said:
«In ten years, CRISPR accuracy will improve to the point where risks are minimal. Parents already pursue every advantage for their children — private schools, tutors, sports. Genetic modification is the logical continuation. The question isn't whether it will happen, but where it will happen first.»
Scenarios for development over the next 20 years
Based on conversations with specialists and an analysis of technological trends, three likely scenarios emerge.
Scenario one: slow legalization. Countries begin to allow embryo editing for a narrow list of severe monogenic diseases. An international registry of modified children is formed, with mandatory lifelong medical follow-up. By 2040, several thousand such children could be born worldwide. The technology remains rare and expensive and is used strictly for medical purposes. Public opinion adapts gradually — similar to the path IVF followed.
Scenario two: genetic tourism. A few countries with liberal legislation — possibly Singapore, the UAE, or small island states — legalize embryo editing with minimal restrictions. A genetic tourism industry forms: wealthy couples travel for enhancement procedures. Other countries ban the import or recognition of such embryos, but enforcement is difficult. By 2040, tens of thousands of genetically modified children could live worldwide, with distribution highly uneven across geography and social class.
Scenario three: technological breakthrough changes the rules. A genome-editing method appears that is an order of magnitude more precise and safer than current approaches. Or a reliable way is discovered to achieve similar effects by editing somatic cells in adults, removing the need for germline modification. The discussion would then shift toward regulating enhancements chosen by consenting adults.
Karina considers the first scenario, with elements of the second, most likely:
«Legalization is inevitable, but it will be slow and cautious. Parallel to that, gray zones will appear — clinics in countries with permissive laws. The main question is whether we'll have time to create international standards before the technology becomes mass-market. If not, it will be too late to regulate effectively.»
Where the line is actually drawn
After conversations with geneticists, I realized the line isn't drawn where laws say it is, nor where public opinion imagines it.
The technical line is between what we can edit precisely and where unpredictable effects begin. Today that is largely monogenic traits; in a decade it could expand toward polygenic traits.
The ethical line is between eliminating suffering and designing desired characteristics. But the definition of suffering is subjective. For some, dwarfism is a condition to be treated; for others, it is an identity that requires no fixing.
The economic line separates what is accessible to all from what only the wealthy can afford. At present, commercial embryo editing is out of reach for most. Technologies tend to get cheaper, but the question is whether society can adapt before biological stratification emerges.
The legal line — between permitted and prohibited — is the most illusory. Laws are national; technology is global. What is banned in Germany may be allowed elsewhere. What is officially banned can still occur in private clinics away from public scrutiny.
The real line lies in whether we are ready to accept responsibility for changing human biology — not in abstract, but as specific people who will live with the consequences of our decisions.
One geneticist told me at the end:
«We can do a lot. The question isn't about the technology — it will develop regardless of our opinion. The question is what kind of society we want to build. One where parents do everything possible for their children's advantage, including altering DNA? Or one where we acknowledge that human dignity does not depend on the genetic code? Technology is neutral. We give it meaning.»
I don't know the right answer. I do know that ignoring the question won't work. The technology is already here. Children with edited genes are already living among us — just a few so far, but this is the beginning. The line will be determined not only by scientific conferences or parliamentary debates, but by the decisions of specific people — scientists, doctors, parents — who every day choose between the possible and the right.
That choice will shape what humanity looks like in a hundred years.
