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Guest author: Jonathan Anomaly

Editor’s note: Fair Start supporters will recognize that Jonathan’s approach could conflict with the Fair Start family planning modeling our organization promotes, but we encourage debate around these issues and appreciate feedback on how readers see PRS technology interacting with values like equity and democracy as we have defined them.


For most of human history, pregnancy was a gamble. It was not unusual for mothers to die from complications associated with childbirth, and it was especially common for their newborn babies to die. Two centuries ago in the United States, nearly half of all children never lived to see their fifth birthday. With the advent of antibiotics and vaccines, pathogens became much less of a threat to young children, lowering infant mortality and extending life dramatically.  

Although we’ve conquered many of the deadliest infectious diseases that used to kill or maim children – including measles, chicken pox, and polio – until recently there was little we could do about genetic predispositions to develop diseases. For a few decades now, fertility specialists have helped parents detect a handful of simple genetic disorders like Tay Sachs disease. Parents can prevent such diseases by testing themselves and potential partners to see if they are carriers, or through the selective implantation of embryos. 

The ability to test embryos for diseases like Tay Sachs has already prevented the needless suffering and premature death of thousands of children. In fact, after only a few decades, genetic testing has reduced the prevalence of Tay Sachs disease in many countries. 

But there is a new and exciting technique that helps parents have children who are likely to live longer and healthier lives. This technique uses polygenic risk scores (PRS) to test embryos for disorders caused by combinations of genes. Unlike Tay Sachs, which is caused by a simple genetic variant, many of the diseases we care about – like cancer, dementia, or heart disease – involve multiple genes interacting in a way that merely elevates the risk that we’ll get these diseases later in life. 

PRS uses information from genomics to predict the likelihood of developing diseases that stem from the interaction of multiple genes. Of course, environmental influences and lifestyle choices also influence the risk of disease. And data derived from analyzing whole genomes isn’t perfect. But as computational biology advances, and genomics becomes more powerful, PRS will become more accurate. Parents who use in vitro fertilization will have more of an opportunity to know what the relevant risks are before they decide to implant an embryo and have a child. 

One current problem with the use of PGS is that most samples come from European populations. This makes sense since much of the early work in genetics has come from Europe and countries with European ancestry. As companies like Orchid Health have argued, we can use the best available data to help pregnant couples now, but also encourage the scientific community to gather more samples from non-European populations so that everyone who wants to can use PRS to mitigate genetic risks. As with other innovations, like cell phones, the initial users actually benefit those who come later as costs decline and the quality of information rises. 

Photo by CDC on Unsplash

Eventually it is likely that parents will want to enhance traits like general immune function, cognition, beauty, and athleticism. Assuming these possibilities become available, we might worry that people will select or edit embryos in a way that decreases genetic diversity. While this is a real possibility, it is worth remembering that people have diverse preferences over the traits of their children, and we already allow people to freely choose mates in ways that have predictable genetic consequences, even if these consequences are unintentional. It is likely that, if given the choice, many parents will select against debilitating diseases, and for traits that enhance the welfare of their children more generally.

If, in the distant future, we discover that parental choices produce patterns that threaten population health in the same way genetically engineered crops can become monocultures that are more susceptible to blight, some form of state intervention might be justified. But as a general rule, parents have better incentives than government agents to figure out what’s best for their children. As moral philosophers like to say, we should generally take the least restrictive alternative among the possible policy interventions that will achieve our goals – in this case, preserving genetic diversity and promoting the welfare of children.

Jonathan Anomaly teaches courses in ethics, political philosophy, and game theory at the University of Pennsylvania. He is the author of Creating Future People: The Ethics of Genetic Enhancement.

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