The Bioethical Debate of the Decade: Choosing a Child's IQ and Height in the Laboratory

One of the most contentious bioethical debates of the 2025–2026 period centers on the emergence of "genetic optimization" for future children. Companies such as the American startup Nucleus Genomics are now offering prospective parents the ability to screen embryos during the IVF process using full DNA sequencing and AI-driven polygenic risk scores. For a price tag ranging from $9,999 to over $30,000, these firms analyze up to 20 embryos to provide a comprehensive comparative report. This data includes risks for over 2,000 medical conditions, as well as physical and cognitive traits like height, eye color, hair color, predisposition to baldness, acne, BMI, and even intelligence (IQ), anxiety, and depression.

The marketing for these services is remarkably direct, utilizing slogans such as "Have your best baby" and "Give your child a smarter start." Similar services are being introduced by companies like Herasight and Orchid. Through dedicated mobile apps, parents are presented with a menu of their potential children: one embryo might show a projected increase of 2.5 cm in height and 2–3 extra IQ points, but with a slightly elevated risk of anxiety. Ultimately, the choice of which embryo to implant is left entirely to the parents, effectively treating genetic traits as customizable options.

The underlying scientific method is known as PGT-P, or preimplantation genetic testing for polygenic traits. The process begins during a standard IVF cycle where multiple embryos are created. A biopsy is performed to collect a few cells from each embryo, which then undergo full genomic sequencing. This is where the technology differentiates itself from traditional screening, as it looks at the entire genome rather than just specific markers.

Once the sequencing is complete, artificial intelligence compares the embryo's DNA against massive datasets from genome-wide association studies (GWAS) involving millions of people. For each embryo, a polygenic risk score (PRS) is calculated. For height, which has a heritability of approximately 80%, the current models explain about 40–50% of the variation; selecting the top embryo out of five typically results in a real-world gain of about 2.5 cm. For intelligence and educational attainment, where heritability is around 50%, the models explain 12–16% of the variation, leading to a potential gain of roughly 2.5 IQ points.

It is important to clarify that this process is not gene editing, such as the controversial CRISPR technology. No new genes are being added, and no existing DNA is being modified. Instead, the technology simply ranks the embryos that the parents have already produced naturally. It is a sophisticated filtering system rather than a biological engineering tool, though the social implications remain just as significant.

Even the strongest proponents of PGT-P acknowledge its substantial limitations. The projected gains in traits like IQ or height are not only small but also probabilistic; the 95% confidence intervals often include the possibility of zero or even negative effects. Furthermore, environmental factors—such as nutrition, education, and social surroundings—have a far more significant impact on a child's development than these marginal genetic advantages. There is also the issue of pleiotropy, where a gene linked to high intelligence might simultaneously increase the risk of psychiatric conditions like schizophrenia.

Additional concerns involve the data itself, as most genetic models are trained on populations of European descent, making them significantly less accurate for other ethnic groups. Furthermore, the long-term outcomes of these selections are entirely unknown, as none of the children born through these methods have reached adulthood. Between December 2025 and February 2026, the American Society for Reproductive Medicine (ASRM) officially stated that the technology is not yet ready for clinical application, citing insufficient evidence regarding its safety and accuracy. While MIT recognized it as a "breakthrough of 2026," they did so with heavy caveats.

This technological leap has reignited a global discussion: is this a form of "new eugenics" or a fundamental right to parental choice? Those supporting the libertarian position argue that parents already make selective choices when picking sperm or egg donors based on education and physical appearance. They contend that this is a private family matter rather than state-mandated social engineering. Proponents like Kian Sadeghi, CEO of Nucleus, argue that using science to prevent diseases like cancer or Alzheimer’s—and giving a child a slightly better cognitive start—is an ethical obligation.

On the other side of the debate, critics and ethicists such as Eric Turkheimer warn that we are entering an era of "voluntary eugenics 2.0." While historical eugenics was state-driven and coercive, this modern version is market-based and exclusive to those who can afford the $10,000 to $50,000 costs. This risks creating a "genetic caste" where the children of the wealthy are systematically taller, healthier, and more intelligent than the rest of the population, potentially deepening existing social inequalities into biological ones.

There are also profound philosophical questions regarding the commodification of human life. When parents are forced to compare 20 embryos across 2,000 parameters, they may face a "decision paralysis" that turns the miracle of birth into a high-stakes consumer choice. Critics argue that this reduces a child to a product designed to meet parental expectations, potentially damaging the parent-child relationship if the child fails to live up to their "optimized" genetic profile. Furthermore, the children themselves never gave consent to have their lives and traits predetermined in a laboratory.

The global regulatory landscape is currently struggling to keep pace with these advancements. There is a clear ethical consensus on using PGT-M to screen against severe monogenic diseases like cystic fibrosis or sickle cell anemia, which is already a worldwide medical standard. However, the use of polygenic screening for common diseases like type 2 diabetes or breast cancer remains a "gray zone" that varies by jurisdiction.

When it comes to pure enhancement—selecting for IQ, height, or personality—most international regulators have drawn a hard line. In the United Kingdom, Australia, Germany, Italy, and much of Europe, such practices are either strictly prohibited or reside in a legal gray area. In the United States, the absence of a federal ban has allowed startups to flourish. Meanwhile, in Singapore, despite various social media claims, the government has not officially authorized the use of these technologies for non-medical traits, and the national debate continues to favor strict limitations on genetic design.