Genetics promises to explain and perhaps prevent many diseases. It also carries a history that should make anyone careful. BIO 101 covers how genes work; this level asks what we should do with what we know.
The shadow of eugenics
In 1883 Francis Galton coined the word eugenics for the project of improving the human stock through breeding. In the early twentieth century eugenics was mainstream science in Britain, the United States and beyond. In Buck v. Bell (1927), the US Supreme Court upheld a Virginia law allowing forced sterilization of people deemed unfit. Justice Oliver Wendell Holmes wrote, "Three generations of imbeciles are enough." Carrie Buck, the young woman at the center of the case, was later found to have been of normal intelligence. Tens of thousands of Americans were sterilized under such laws, and Nazi Germany cited American examples when it built its own program, which led to mass murder.
The lesson most bioethicists draw is not that genetics is evil but that state control of reproduction, judgments about which lives are worth living and confident science can combine terribly. Some warn that a new, liberal eugenics may arrive through private choices rather than state force.
Testing and the right not to know
Genetic tests can reveal risks that cannot be changed. Huntington's disease, for example, is caused by a single gene and is incurable. Many people at risk choose not to be tested, and clinics defend a right not to know. Results also affect relatives, who share genes, and insurers and employers would like them. In the United States, the Genetic Information Nondiscrimination Act of 2008 bans genetic discrimination in health insurance and employment, but GINA does not cover life, disability or long-term care insurance. Consumer genetic testing raises further questions about who owns the data and what happens to it when a company is sold.
CRISPR
In 2012 Jennifer Doudna and Emmanuelle Charpentier showed that a bacterial defense system called CRISPR-Cas9 could cut DNA at a chosen spot, making gene editing far easier and cheaper. They won the 2020 Nobel Prize in Chemistry. Ethicists distinguish two kinds of editing. Somatic editing changes cells in one patient's body. Germline editing changes eggs, sperm or embryos, so the changes are passed to future generations. Somatic editing raises familiar questions about safety and consent. Germline editing affects people who cannot consent and may never be reversed.
The first approved CRISPR treatment, Casgevy, was licensed in Britain in November 2023 and in the United States the next month. Casgevy treats sickle cell disease and a related blood disorder by editing a patient's own blood stem cells. Its list price in the United States, around two million dollars, sharpened the question of who will benefit.
The He Jiankui affair
In November 2018 the Chinese scientist He Jiankui announced the birth of twin girls whose embryos he had edited. He tried to disable the gene CCR5 to make them resistant to HIV infection. The reaction from scientists worldwide was almost entirely condemnation. There was no unmet medical need: the father had HIV, but safe methods already exist to prevent passing it to children. The editing was incomplete in at least one twin, its effects on other genes were unknown, consent forms misled the parents, and the work was done in secret. A Chinese court sentenced him in 2019 to three years in prison. The case strengthened support for existing bans, such as the Council of Europe's Oviedo Convention of 1997, which forbids heritable genetic changes in countries that ratified it.
Therapy, enhancement and the future
Suppose germline editing became safe. Would it be acceptable to prevent a fatal disease? To raise intelligence? Some philosophers, such as Julian Savulescu, argue that parents have reason to choose the children with the best chances of a good life. Michael Sandel replies that the drive to master our children's traits erodes the humility of accepting children as gifts and burdens parents with responsibility for every trait. Others raise justice: if enhancements are expensive, inequality could become biological. Disability scholars ask who decides which traits are defects. Many people accept editing to prevent serious disease while rejecting enhancement, though the line between the two is disputed. TECH 101 covers related debates about technology and human nature.
Worked example: a family with Huntington's
A twenty-eight-year-old man's mother has Huntington's disease, so he has a fifty percent chance of carrying the gene. He wants children but does not want to know his own status. His clinic can test his embryos during IVF and transfer only those without the gene, without telling him whether any carried it. This is called exclusion testing. It respects his right not to know while preventing the disease in his children. It uses screening, not editing, so no future generation inherits an engineered change. Even so, the questions from this level apply. Is he free from pressure from his partner or family? Is the procedure affordable for families like his everywhere, or only for the wealthy? And how would the answers change if, years from now, editing the gene out of an embryo became possible?