Designer Babies

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Date: 2019
Publisher: Gale, a Cengage Company
Document Type: Topic overview
Length: 2,274 words
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Designer babies are babies whose genetic makeup was selected or modified at the embryo stage to ensure the presence or absence of certain characteristics. To create designer babies, scientists use a combination of genetic engineering and reproductive technologies in vitro, which are processes that take place outside of the human body in a laboratory setting. Prospective parents who carry genes associated with inherited diseases, for example, may choose to use genetic technologies to select or alter embryos to avoid passing the condition down to their children. The first designer baby, Adam Nash, was born in 2000 after researchers at the Reproductive Genetics Institute in Chicago, Illinois, used genetic screening to select an embryo without the marker for Fanconi anemia, a rare disease from which his older sister, Molly, suffered. Because stem cells from Adam's umbilical cord were used to treat Molly's disease, he is also known as the first savior sibling, a term for designer babies whose conception was at least in part motivated by a sibling's need for compatible donor material.

Genetic engineering has evolved since Nash's birth, and researchers believe that advancing technologies could potentially be used to design babies with attributes or capabilities that exceed the normal range of human function. The emergence of the gene-editing technique CRISPR-Cas9 in the early 2010s and reports of the first "CRISPR babies" being born in China in November 2018 have reinvigorated debates over the ethics of intentionally modifying genetic material. Supporters assert that it holds the promise to increase human potential, eliminate disease and disability, improve quality of life, and strengthen the human gene pool. Critics, on the other hand, argue that it has the potential to disrupt natural biological processes and create unforeseeable risks. While most bioethicists note that it is possible to use these practices in ethical ways to prevent suffering, they caution that, when undertaken for other purposes or in the absence of a solid ethical framework, genetic editing could have far-reaching negative, unintended consequences. Altering the genetic material of embryos to optimize socially desirable or individually preferred traits such as intelligence, athleticism, sex, or eye color, for example, is ethically questionable, critics claim, because it is likely to worsen discrimination and inequality.

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Pros and Cons of Genetic Modification of Human Embryos


  • Genetic modification of human embryos holds the promise to increase human potential, strengthen the human gene pool, and raise the overall quality of life for humanity.
  • Genetic modification of human embryos may enable us to eradicate genetic disorders, eliminate disability, provide immunity against infectious diseases, and ease suffering.
  • Genetic modification of human embryos could be used to imbue future generations with attributes or capabilities that exceed the normal range of human function.


  • Genetic modification of human embryos is comparable to "playing God," disrupts natural biological processes, and makes permanent changes to which the embryo cannot consent.
  • Genetic modification of human embryos involves interfering with the germline in ways that cannot be controlled, which could lead to unforeseeable and irreversible risks.
  • Genetic modification of human embryos to enhance or optimize desirable traits like intelligence or athleticism has the potential to create new kinds of social inequality.

Methods and Uses of Genetic Screening

The genetic interventions that are involved in the creation of designer babies are performed during in vitro fertilization (IVF), an assisted reproduction procedure in which human eggs are removed from the ovary or ovaries and fertilized with sperm in a laboratory to form embryos. One or more of the embryos are typically selected for transfer to the uterus. In a successful IVF cycle, transferred embryos will implant in the wall of the uterus, develop into a fetus throughout pregnancy, and result in a live birth. Spare embryos may be preserved for future use, donated, or discarded. Since it was first performed successfully in 1977, IVF has become a standard medical treatment for infertility.

The IVF process makes it possible to assess the genetic characteristics of embryos in the laboratory prior to implantation. One reproductive technology used to screen embryos, preimplantation genetic diagnosis (PGD), involves extracting a cell from an IVF embryo to test for specific genetic defects that increase the risk of developing certain inherited diseases, such as cystic fibrosis, hemophilia, sickle-cell anemia, or Tay-Sachs disease. Prospective parents who carry the genes associated with these conditions may use PGD to identify and select embryos without a genetic predisposition or defect, such as in the case of Adam Nash.

A similar procedure known as preimplantation genetic screening (PGS) involves testing the entire genome of an IVF embryo for chromosomal abnormalities, which are associated with Down syndrome and other genetic disorders. Rather than look for a specific disease-causing gene, PGS evaluates the health of the embryo in a more general way. Because the risk of chromosomal abnormalities increases with maternal age, PGS is often used by prospective mothers over age thirty-seven to select embryos with normal chromosomal arrangements for implantation. Because the cell biopsies performed during PGD and PGS can traumatize the embryo, these procedures are usually reserved for identifying genetic defects and reducing disease risk.

Genetic Modification of Human Embryos

Advances in the field of genetic engineering have made it possible to modify or alter the genes of living organisms. One of the most promising gene-editing technologies implements clustered regularly interspaced short palindromic repeats (CRISPR), which involve a repeating sequence of genetic code that is extracted from bacteria. Scientists can program CRISPR to target specific DNA sequences in living cells and use an enzyme to make precise cuts in the DNA strands. Known as the CRISPR-Cas9 technique, it can be used to delete, replace, or insert new genes, causing permanent changes to the organism's genetic code.

Genetic modification has been performed extensively on plants and animals to impart disease resistance and increase food production, yet ethical concerns and legal prohibitions have historically limited experimentation on humans in clinical trials to gene therapy—applications that use a virus as a vector to deliver healthy DNA to cells in an effort to treat disease. Gene therapy is used to affect somatic cells, which are the differentiated cells that make up major organs like the eyes or lungs, so the changes only affect the individual who undergoes the procedure. When genetic engineering is performed on reproductive cells, such as eggs, sperm, or early-stage embryos, however, the genetic changes and any resulting effects are passed down to future generations. Genetic engineering that produces heritable changes to DNA is known as germline modification.

In July 2017, a team of researchers in Oregon announced that they had successfully used the CRISPR technique to modify the genes of dozens of human embryos. The embryos were created for the experiment through IVF using eggs and sperm donated by people who carried genetic diseases. After the scientists edited the genomes to correct the faulty genes, they destroyed the embryos in accordance with US law to prevent the changes from permanently modifying the germline.

A scientist at Southern University of Science and Technology (SUSTech) in Shenzhen, China, caused global controversy in November 2018 when he announced the first live birth of babies—twin girls—whose genes had been edited as embryos using CRISPR. The embryos were edited to disable the CCR5 gene with the hope of creating resistance to HIV. Although some researchers were cautiously optimistic and compared the breakthrough to the birth of Louise Brown, the first baby to be conceived using IVF, He Jiankui, the scientist at the helm of the study, was met primarily with condemnation from bioethicists and fellow scientists. David Baltimore, chair of the Second International Summit on Human Genome Editing, referred to He's study and the birth of the babies as "a failure of self-regulation by the scientific community," and both SUSTech and the Chinese government launched investigations into He's actions. According to China's state-run news agency Xinhua, the government concluded in January 2019 that He had acted "in the pursuit of personal fame" and had violated "ethical principles and scientific integrity."

SUSTech terminated He's employment. Researchers in the United States who had been involved with or aware of He's experiments have also faced criticism and calls for accountability, with Rice University in Texas launching an investigation into He's former advisor, Michael Deem, in November 2018. While the Chinese government's report appears to confirm that the babies exist, as of February 2019, He's experiment had not been published or officially peer-reviewed. The lack of publicly available information has prevented other researchers from offering an informed, accurate assessment of the experiment's methods, results, and safety.

Arguments Against Genetic Modification

The creation of genetically modified human embryos raises many ethical questions. CRISPR technology gives scientists the ability to permanently change the genetic makeup of a human being, as well as that person's future offspring. Germline modification is so new and untested, according to opponents, that its unpredictable results may expose future generations to unforeseen risks that outweigh any potential benefits. Many countries have outlawed or placed a moratorium on germline modification of embryos. In the United States, discomfort with the idea convinced Congress to pass a bill in 2015 that prohibits the Food and Drug Administration (FDA) from approving clinical trials that would produce genetically modified human embryos. That year, the National Institutes of Health (NIH) also affirmed its ban on genetic editing of human embryos, but in 2016 the NIH approved a clinical trial of CRISPR gene-editing technology as a therapy for cancer patients. The following year, the US National Academy of Sciences released an advisory statement supporting limited research into embryonic genetic modification for the purpose of eliminating disease.

Although proponents envision CRISPR being used to correct genetic defects and eradicate inherited diseases, critics foresee the possibility of nontherapeutic uses like optimizing socially and culturally desirable traits. They argue that, because the personal expense associated with IVF procedures would make such enhancements an option only for wealthy families, using genetic modification for these purposes could create a two-tiered society in which poor people and marginalized groups would face insurmountable genetic disadvantages. Other critics fear that governmental entities could misuse gene-editing technology to create a "superhuman" germline with improved strength and endurance for military purposes.

Some people object to genetic enhancement on moral or ethical grounds. They argue that scientists should not "play God" by interfering with biological processes and changing the natural progression of human evolution. They claim that routine correction of genetic differences could reduce the diversity of the human gene pool and leave everyone vulnerable to new diseases and environmental threats. Some disabled people with conditions that have been linked with particular inherited genetic markers resist the idea of genetic intervention as well. They argue that it promotes the view that their lives are inherently inferior, of lesser value, or not worth living, and contributes to widespread ableism, which refers to discriminatory attitudes and acts against disabled people. Disability rights activists warn that such attitudes have been used historically to justify and normalize unethical practices like nonconsensual sterilization.

Concerns about the genetic modification of human beings are widespread in the United States, with the public's support depending largely on the purpose of such modifications. A 2018 poll conducted by the Pew Research Center, for example, found that 72 percent of US adults believed that changing a baby's genetic characteristics was appropriate if intended to treat a serious condition the baby would have at birth, with support declining to 60 percent if modifications were intended to reduce the risk of a disease that could occur over the baby's lifetime. Despite relative support for these purposes, however, 80 percent of respondents indicated that changing a baby's genetic characteristics to make the child more intelligent would be taking genetic engineering technology too far, and only 33 percent of respondents indicated support for testing on human embryos to advance gene-editing technologies.

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Critical Thinking Questions

  • What are survivor siblings, and do you think that the practice of making survivor siblings is ethically justifiable? Explain your answer.
  • Why do you think that public support of continued research into genetic modification varies depending on the purpose of the research?
  • In your opinion, should scientists be mandated to destroy human embryos on which they have used the gene-editing technique CRISPR-Cas9 after a certain number of days? Why or why not?

Arguments in Support of Genetic Modification

Genetic modification receives a great deal of support within the scientific community, as well as from adherents of the intellectual movement known as transhumanism. Transhumanists believe that resources should be dedicated to developing new technologies that can eliminate physical and intellectual limitations and increase human potential. They view genetic enhancement as a valuable tool in the pursuit of this goal. Supporters in the scientific community argue that genetic modification of embryos has the potential to cure inherited diseases and disorders and increase the quality of life for generations of people. They promote responsible research aimed at improving human health and welfare.

Advocates of genetic engineering also point out that parents have a natural desire to produce children who are strong, healthy, intelligent, and attractive. Many people exercise their reproductive freedom to choose mates that are likely to imbue their children with these desirable qualities. Proponents claim that genetic enhancement is another tool for people to use to select or improve upon certain traits in their offspring. They argue that creating designer babies should be a personal choice for parents to make without judgment from society or interference from regulatory bodies. Advocates also note that many people take steps to improve themselves as adults. For instance, they apply makeup to appear more attractive, exercise to increase their physical fitness, and pursue education to increase their intelligence. Since society generally approves of these efforts and views self-improvement as a worthwhile goal, proponents argue that genetic enhancement may enjoy greater public acceptance as the technology continues to develop and becomes more commonplace.

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Gale Document Number: GALE|PC3010999192