What Are the Pros to Designer Babies?

The strongest case for so-called designer babies is the prevention of serious genetic disease. Technologies that already exist, particularly embryo screening during IVF, allow parents who carry mutations for conditions like cystic fibrosis, sickle cell disease, or Huntington’s disease to have biological children free of those disorders. Newer tools like CRISPR-based gene editing and mitochondrial replacement push the boundary further, raising the possibility of correcting mutations that screening alone cannot address. The conversation gets more speculative, and more contentious, when it moves beyond disease prevention into territory like cognitive traits or lifespan, but the medical arguments for the technology’s core use cases are grounded in decades of clinical data.

Preventing Inherited Single-Gene Diseases

The most established benefit is the ability to prevent monogenic disorders, diseases caused by a mutation in a single gene. Preimplantation genetic testing for monogenic disorders, known as PGT-M, works by screening IVF embryos before transfer and identifying those that carry the disease-causing mutation. Only unaffected embryos are implanted. This approach is now widely used to prevent conditions ranging from hereditary neurological diseases to metabolic disorders that primarily affect the nervous system.¹ Over the past three decades, PGT has broadened considerably in scope, with the number of embryos undergoing genetic testing growing every year.²

For families who have already watched a child suffer through a devastating genetic condition, this screening can be transformative. It provides a path to a biological child without the anxiety of prenatal diagnosis and the wrenching decision about whether to terminate a pregnancy. Research reviewing the psychological impact of PGT found that parents consistently cited the ability to establish a pregnancy without facing potential termination as a major advantage, along with the reduced stress of knowing ahead of time that a disorder had been avoided.³

Screening Out Cancer Predispositions

PGT was originally developed for early-onset, clearly defined genetic conditions, but its use has expanded to include inherited cancer syndromes. Families carrying mutations in genes like BRCA1 or BRCA2, which dramatically raise the risk of breast and ovarian cancer, can now use PGT to select embryos that do not carry those mutations.⁴ This is a different kind of prevention than screening for a disease that will definitely manifest. A BRCA mutation does not guarantee cancer, but it raises lifetime risk so substantially that many carriers opt for prophylactic surgery. Being able to spare a child that burden entirely, before they are even born, is a meaningful benefit that already exists in clinical practice.

Mitochondrial Replacement and “Three-Parent” Babies

Some inherited conditions cannot be caught by standard embryo screening because they are not carried in the nuclear DNA that PGT examines. Mitochondrial diseases, caused by mutations in the small set of genes inside mitochondria, are passed from mother to child through the egg cell. The symptoms range from muscle weakness and seizures to organ failure, and there is no cure.

Mitochondrial replacement therapy offers a workaround. The mother’s nuclear DNA is transferred into a donor egg that has healthy mitochondria, producing an embryo with genetic material from three people: nuclear DNA from both parents and mitochondrial DNA from the donor. The goal is to reconstruct a functional egg or embryo so the child does not inherit the mutated mitochondrial genes.⁵ This technique is already permitted in the United Kingdom and has been used in a handful of clinical cases. While still in its early stages, it addresses a category of genetic disease that no other reproductive technology can currently prevent.⁶

Engineering Resistance to Infectious Disease

The most controversial real-world case of genetic engineering in human embryos was motivated by a pro that is easy to understand: resistance to HIV. In 2018, He Jiankui used CRISPR to edit the CCR5 gene in human embryos, resulting in the birth of two baby girls with man-made mutations in that gene.⁷ CCR5 encodes a protein on the surface of immune cells that HIV uses to enter and infect them. People born with a naturally occurring deletion in CCR5 are substantially resistant to the most common strain of HIV. That discovery had already prompted research into CCR5-based therapies and genome editing in animal models as a potential strategy for treating or preventing HIV infection.⁸

He Jiankui’s experiment was widely condemned for reckless execution, not because the underlying goal was absurd. The idea that gene editing could protect people from serious infections has genuine scientific backing. The problem was that the risks of off-target edits and unknown long-term consequences far outweighed the benefits for those particular children, who were not at especially high risk of HIV. But in a future where the tools are more precise and the target population is genuinely at risk, conferring heritable resistance to deadly infections is one of the clearest theoretical advantages of germline editing.

The Economic Argument

Genetic screening and selection also carry a public health economic case that is hard to ignore. Treating a serious genetic disease across a patient’s lifetime can cost hundreds of thousands or even millions of dollars. One Australian economic evaluation found that expanded reproductive carrier screening, combined with IVF and preimplantation testing, would avert roughly a third of affected births in a single birth cohort and reduce lifetime health service spending by over 600 million Australian dollars.⁹

This resonates powerfully with families who have lived through it. In interviews, couples who used PGT described their frustration that insurance companies would reimburse hundreds of thousands of dollars, and in one case nearly a million, for surgeries and treatments related to a child’s genetic disorder, but would not cover the roughly $20,000 cost of IVF and genetic testing that could have prevented the disorder entirely.¹⁰ The cost-effectiveness argument applies not only at the individual level but at the system level, where even modest uptake of screening can yield significant savings.

How Children Born After Genetic Testing Are Doing

A reasonable follow-up question is whether children born after embryo selection are healthy and developing normally. The evidence so far is reassuring. A national register-based study comparing children born after PGT with children conceived through standard IVF found no significant differences in early childhood health outcomes. Rates of asthma, allergic disorders, and other conditions were comparable between groups, and none of the PGT children in the study died during the follow-up period.¹¹

Broader reviews of children conceived through IVF in general have also found encouraging results. After 25 years of follow-up studies, mental and motor development during infancy and preschool years appeared normal, as did cognitive development at age five. Psychosocial well-being was comparable to naturally conceived children up to age eight, and while some slight indications of social-emotional differences emerged at older ages, a large study on adolescents found psychological functioning to be reassuring overall.¹² These data address one of the most understandable concerns parents have: that the process of screening and selecting embryos might somehow harm the child who results from it.

The Ethical Framework of Procreative Beneficence

Philosopher Julian Savulescu formalized an argument that gives the pro-designer-baby position its most ambitious intellectual grounding. His Principle of Procreative Beneficence holds that parents should select, from the embryos available to them, the child expected to have the best life, based on all relevant genetic information, including information about non-disease genes.¹³ This extends the logic of disease prevention into more controversial territory. If it is good to screen out a mutation for muscular dystrophy, Savulescu argues, why not also consider genes associated with intelligence or temperament?

This principle has been seriously debated in bioethics for over two decades. Some scholars have argued that the logic of procreative beneficence, taken to its full conclusion, implies not just selecting embryos for traits like intelligence but an obligation to genetically engineer embryos for such traits when the technology permits.¹⁴ Whether you find this compelling or alarming depends heavily on your values, but the framework does force a useful question: if we already accept selecting embryos to avoid disease, where exactly is the principled line between prevention and enhancement?

Lifespan and Healthspan

One of the more speculative but scientifically grounded arguments for genetic enhancement involves aging itself. Researchers have identified families of genes, sometimes called gerontogenes, that influence DNA repair, cellular stress responses, and key signaling pathways tied to how quickly cells and tissues age.¹⁵ Animal and cell-culture studies have begun to identify specific gene targets for potential longevity therapies.¹⁶

Some results from laboratory work are striking. Researchers have shown that a single-nucleotide edit in the NRF2 gene, a transcription factor involved in protecting cells from oxidative stress, can improve the self-renewal ability, stress resistance, and delayed aging of human stem cells. In mouse experiments, cells carrying the enhanced NRF2 gene showed improved survival and blood vessel regeneration. Even when exposed to powerful cancer-promoting signals, the enhanced cells did not form tumors, while unmodified cells did within weeks.¹⁷ This is far from a clinical therapy for human embryos, but it illustrates the kind of targeted improvement that gene editing could theoretically deliver: not just avoiding a specific disease, but building in greater biological resilience.

What About Intelligence and Cognition?

Enhancement advocates sometimes point to cognitive traits as a frontier for genetic selection. The science here is much weaker than the rhetoric suggests. Intelligence is influenced by thousands of genetic variants, each contributing a tiny effect. Polygenic scores, which aggregate these tiny effects into a single number, can currently explain only a few percent of the variation in IQ between people. In one deep-phenotyping study, the best-performing polygenic score explained about 4% of the variation in general intelligence.¹⁸ The researchers noted that these scores do not reflect different facets of intelligence equally well and should not be treated as genetic indicators of intelligence in any meaningful individual sense.

Modeling studies have estimated what would happen if parents undergoing IVF used polygenic scores to select embryos. The predicted gain is modest: roughly three IQ points on average when using a full genome-wide score to choose among a typical number of embryos.¹⁹ Three points is within the noise of a single IQ test, smaller than the effect of ordinary environmental factors like nutrition or education quality. The theoretical pro exists, but the practical payoff is currently tiny, and the science underlying polygenic prediction for complex traits is still evolving rapidly.

Improving the Precision of the Tools

One of the original concerns about CRISPR-based gene editing in embryos was that the tools were too imprecise. Early experiments suffered from low efficiency and mosaicism, a situation where some cells in the embryo carry the intended edit and others do not, producing an organism with a patchwork of edited and unedited cells. More recent work with refined delivery methods and newer editing tools like base editors and prime editors has improved precision considerably.²⁰

Prime editing, in particular, has shown promise. Whole-genome sequencing of human embryonic stem cells edited with a prime editor found that, unlike some other editing approaches, the prime editor’s core machinery did not cause random off-target mutations elsewhere in the genome.²¹ This is a meaningful safety advance. The steady improvement in editing accuracy is itself a pro in the broader argument: the risks that make germline editing unacceptable today are being systematically reduced, which strengthens the case that the technology’s benefits will eventually be safely deliverable.

The Regulatory Picture

Understanding where these technologies stand legally matters for evaluating their practical benefit. A survey of 96 countries with relevant policy documents found that 75 prohibit using genetically modified embryos to initiate a pregnancy, and no country explicitly permits heritable genome editing.²² Eleven countries, including the United States, the United Kingdom, Japan, and China, do allow germline editing experiments in a research context, though with varying levels of oversight.²³

Since the He Jiankui scandal, there have been no international treaties or major changes in hard law among the leading research nations. The most significant regulatory development was China’s 2024 expansion of ethical review measures for gene editing research, which now covers a broader range of activities involving human cells, tissues, and embryos and requires enhanced informed consent.²⁴ The regulatory environment reflects a global consensus that the tools are promising but not yet safe or well-understood enough for reproductive use. That is a genuinely reasonable position, and it means the pros discussed throughout this article remain largely prospective rather than immediately available for most applications beyond PGT.

Access and Equity as a Double-Edged Benefit

The benefits of designer baby technology only count as benefits if people can actually access them. Right now, they cannot do so equally. A study of infertility patients in the United States found that the likelihood of receiving genetic carrier screening varied dramatically by race and income. About 73% of white respondents had received screening, compared with roughly 45% of Black respondents and 49% of Hispanic respondents. Income and insurance status were also significant factors.²⁵

A systematic review of ethical arguments around embryo editing flagged socioeconomic inequity as a central concern: high costs and insurance limits could mean affluent individuals gain disproportionate access.²⁶ This matters for how we evaluate the pros. Preventing genetic disease is unambiguously beneficial for the families who can use the technology. But if access remains stratified by wealth and race, the population-level benefit shrinks, and the technology risks deepening existing health disparities rather than closing them. The pro is real, but its reach depends entirely on policy choices that have not yet been made.

Human Enhancement Beyond Disease

Supporters of genetic enhancement technologies take a broader view than disease prevention alone. The argument, as articulated in the bioethics literature, is that humans have always used available tools to overcome natural limitations and that genetic engineering is simply the next step in that trajectory. Proponents frame enhancement as any genetic, biomedical, or pharmaceutical intervention aimed at improving human capacities or well-being, even when there is no disease being treated. The scope of what counts as a legitimate “improvement” can shift with the environment: climate change, novel pathogens, or other ecological pressures could create scenarios where genetic adaptations offer survival advantages that natural selection would take generations to produce.²⁷

This is where the conversation moves from the concrete to the philosophical. Preventing Huntington’s disease in a child who would otherwise certainly develop it is a clear benefit with a clear mechanism. Giving a future child marginally better stress resistance or slightly improved cardiovascular health through a genetic tweak that has only been tested in mice is a different proposition entirely. The strength of the “pro” argument scales directly with how well-understood and proven the intervention is. For single-gene diseases, the case is strong and the evidence is solid. For complex traits and enhancement, the case is intellectually interesting but practically thin. Honest advocates for the technology acknowledge both realities rather than pretending the science is equally mature across the board.