General · EdgepediaSeptember 17, 20268 min read

Designer baby

A designer baby is a baby whose genetic makeup has been selected or altered before birth, typically through embryo screening during in vitro fertilization (IVF) or, in principle, through direct genome editing, to include particular traits or to remove genes associated with disease¹^•². The traits discussed range from lowered disease risk to sex selection¹. The term itself was coined by journalists: after the first births following preimplantation genetic testing in 1990, extensive publicity about the possibility of using IVF and embryo testing for characteristics not related to health, such as sex selection, produced the epithet "designer babies", which has continued to resonate³.

Key fact	Detail
Definition	A baby genetically engineered in vitro for specially selected traits, from lowered disease-risk to gender selection¹
First clinical use	First pregnancies and live births after IVF and preimplantation genetic testing reported in 1990, in couples at risk of X-linked conditions, by identifying embryo sex and avoiding transfer of males³
Approved testing scope	Over 2,000 genetic conditions approved for PGT-M testing in the United Kingdom; testing requires IVF even when the parents have no fertility problems⁴
Polygenic selection limits	For children of biologic parents of European ancestries, the 95% prediction interval of actual gain in educational-attainment score ranges from +4.2 years to −3.2 years⁵
Gene-edited births	In 2018, He Jiankui announced the birth of twins whose CCR5 gene had been edited with CRISPR-Cas9, aiming at HIV resistance; the Chinese government prohibits genetic manipulation of gametes, zygotes, and embryos for reproductive purposes, and his operations violated existing regulations⁶
Governance position	The US National Academies and the UK Nuffield Council found that if germline editing were ethically defensible, it would have to be limited to changes for the welfare of the future child⁷
Moratorium	Scientific societies called in mid-2025 for a 10-year moratorium on heritable genome editing⁸

Techniques

Embryo selection. The established route to a "designed" child is selection rather than engineering. In preimplantation genetic testing for monogenic disorders (PGT-M), previously called preimplantation genetic diagnosis, a cell is removed from an IVF embryo and tested for a specific genetic condition; embryos free of the condition are transferred to the womb⁴^•⁹. The 1990 cases used the simplest form of this logic: at the time it was possible only to identify the sex of the embryo, so couples at risk of X-linked conditions that typically affect boys could avoid transferring male embryos, half of which would have been affected³. In the United Kingdom, PGT-M is permitted only for conditions that meet legal criteria on the risk of transmission and the seriousness of symptoms, and over 2,000 conditions have been approved⁴.

Polygenic embryo selection. A newer extension scores embryos using polygenic scores, which summarize the combined small effects of many genetic variants on a trait⁵. Companies now offer assessments of intelligence, height, or the risk of certain cancers and alcohol addiction using such scores, whose relevance is disputed and which are banned in France⁸. The predictive power is limited in practice. For educational attainment, the 95% prediction interval of actual gain for children of European-ancestry parents runs from +4.2 years to −3.2 years, meaning an embryo chosen for a high score may realize a substantial loss⁵. Height is the best-case trait, because it is easy to measure and strongly genetic: in the U.S., about 80% of variation in height is due to DNA¹⁰. For most traits people are interested in, accuracy is quite limited, and when only a few embryos are available, picking the highest-scoring one produces only a small average change¹⁰. Pleiotropy adds a further complication: an embryo selected for one trait may carry unusually high or low scores for other traits the parents did not intend to target⁵.

Genome editing. Direct editing of embryos with tools such as CRISPR-Cas9 would go beyond selection by altering the genome itself, and because germline changes are heritable, it raises distinct safety and consent questions¹¹. The National Institutes of Health stated that it will not fund any use of gene-editing technologies in human embryos, citing serious and unquantifiable safety issues, the ethical problem of altering the germline in a way that affects the next generation without their consent, and a lack of compelling medical applications justifying CRISPR/Cas9 in embryos¹². Research findings from 2017 indicated that a trait deliberately introduced into a human embryo might fail to be expressed, with the variant on the other chromosome being expressed instead, which could undermine attempts to design the resulting child⁷.

The He Jiankui case

The publicly claimed gene-edited babies came in November 2018, when He Jiankui of the Southern University of Science and Technology in Shenzhen announced at the Second International Summit on Human Genome Editing in Hong Kong that twins had been born after CRISPR-Cas9 editing of the CCR5 gene in embryos, with the goal of disabling the gene so the babies would avoid infection with HIV⁶^•¹³^•²¹. The international scientific community condemned the work as irresponsible and unethical¹³. The Chinese Academy of Medical Sciences stated its opposition to any clinical operation of human embryo genome editing for reproductive purposes in violation of laws, regulations, and ethical norms, noting that the Chinese government prohibits genetic manipulation of human gametes, zygotes, and embryos for reproductive purposes and that He's operations violated regulations including the 2003 ethical guiding principles and the 2017 Safety Management Measures for Biotechnology Research and Development⁶.

Ethical debate

Eugenics. Because selecting embryos for preferred traits echoes historical eugenics programs, much of the debate turns on whether the term applies and what exactly is objectionable in it. Stephen Wilkinson distinguishes objections to eugenic ends from objections to the means of achieving them, and examines an argument against using preimplantation genetic diagnosis to screen out disability based on the Equal Value Principle, which says that disability and non-disability should be valued equally¹⁴. The disability rights critique of what is sometimes called liberal eugenics targets current practices such as prenatal testing, preimplantation genetic testing, selective abortion, and gene editing, and calls attention to prejudices against people with disabilities among the professionals who administer these tests¹⁵.

The expressivist argument. Under the expressivist argument, opting to deploy biotechnologies so that individuals with particular disabilities are never born conveys a message that the lives of people already living with those disabilities are of less value. Analysis of the argument shows it has a wide range of underpinnings, while counter-arguments tend to address only a few of them¹⁶.

Open future and welfare. Critics of germline editing argue that it interferes with what the philosopher Joel Feinberg called a child's right to an open future: children possess anticipatory autonomy rights that are violated when their opportunities in life are limited by circumstances at birth⁷^•¹². On the other side, the National Academies and the Nuffield Council concluded that germline editing could be defensible if limited to changes for the welfare of the future child, encompassing prevention of serious disease and disability, while enhancement of otherwise healthy conditions, the possibility often described as creating designer babies, strikes many as an intrusion on autonomy and a threat to social stability⁷. Philosophers of the procreative-benefit view have argued for a moral obligation to create children with the best chance of the best life, while treating disability as context- and person-relative rather than privileging the normal¹⁷.

Inequality and access. Commentators also weigh whether enhancement would widen social inequality, and whether a market in designed children could enable coercive or state-controlled eugenics¹⁸^•¹⁹.

Regulation

Rules vary widely. In the United Kingdom, embryo testing for serious inherited disease is licensed and condition-by-condition approved by the Human Fertilisation and Embryology Authority, and the country has allowed the birth of "three-parent children" in cases of mitochondrial disease⁴^•⁸. France bans polygenic embryo scoring⁸. Japan revised its gene therapy regulations in 2019 to address genome editing, explicitly prohibiting germline modification²⁰. Creating genetically modified babies is widely prohibited, and scientific societies called in mid-2025 for a 10-year moratorium on heritable genome editing, warning of a slippery slope from addressing severe genetic disease toward the pursuit of specific traits⁸.

References

Topic: Encyclopedia › Life and health › Applied biology and nonhuman health › Biotechnology and biological production › Biotechnology regulation, law, and ethics › Biotechnology ethics and controversies

Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 21, 2026 · Edited: Sep 30, 2026; Oct 15, 2026; Oct 21, 2026 · Last review: Oct 21, 2026

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