Emerging embryo-selection technologies are currently 'little more than snake oil.' But someday, they could widen social inequities.

The technology sounds like it's been plucked from a science-fiction film — but it's all too real.

A number of companies now offer prospective parents the chance to "score" embryos fertilized through in vitro fertilization (IVF), based on the embryos' genetic profiles. This technology, called polygenic embryo selection, uses genetics to predict the likelihood that a given trait or disease will manifest in a baby-to-be. In theory, the technology could be leveraged to lower a child's risk of diseases with strong genetic components. But there are lingering questions about how well it works and whether it could deepen existing health disparities between groups.

Bioethicist Daphne Martschenko and sociologist Sam Trejo explore some of these questions in this excerpt from their book "What We Inherit: How New Technologies and Old Myths Are Shaping Our Genomic Future" (Princeton University Press, 2026).

For most traits and diseases, companies offering polygenic embryo selection are currently selling consumers little more than snake oil. However, in the coming decades, the accuracy of polygenic scores will likely improve. These improvements in accuracy will mean that a wider range of characteristics will become viable targets for polygenic embryo selection, raising a host of concerns. Among them, first and foremost is the potential exacerbation and, worse still, biological reification of structural inequality that could come from unequal access to the technology.

If the United States continues on its current path, polygenic embryo selection will only be available to those with enough money to afford IVF and will — at least for a time — be most effective in individuals of European ancestries. The high costs of IVF are prohibitively expensive for working- and middle-class Americans. A single cycle of IVF costs between $15,000 and $20,000 — and, at present, most couples undergoing IVF go through three or four cycles to be successful, with extra costs incurred to freeze embryos or use donor eggs. (However, because these couples are typically experiencing infertility, the extent to which these figures generalize the broader American population of prospective parents is uncertain.) Private health insurance coverage of IVF is typically limited and varies across states and employers. Medicaid, the public health insurance offered to low-income families in the United States, does not cover IVF at all.

Polygenic embryo selection only introduces further additional costs; Genomic Prediction, for instance, charges $1,000 per embryo analyzed, and Orchid Health charges $2,500. Heliospect charges up to $50,000 to test 100 embryos. If the status quo continues and polygenic embryo selection remains unregulated, then unequal access to the technology will cause structural inequality to grow. The racial and socioeconomic disparities of the world, both past and present, are not the result of systematic DNA differences across groups. If polygenic embryo selection continues to expand unchecked, then the frightening possibility exists that a new source of racial and economic structural inequality that is, in part, genetically produced will emerge.

As an example, consider health disparities. Because of the portability problem, polygenic embryo selection has decreased effectiveness in non-European ancestries. If, in the coming years, the use of the technology grows, those of non-European ancestries, like Pacific Islander Americans, will largely be excluded from any health benefits that embryo selection provides. Pacific Islander Americans (such as those from Guam or Samoa) are largely of Oceanian ancestries and occupy a unique portion of the Family Tree. They tend to have higher rates of diabetes, high blood pressure, and heart disease than White Americans — the Centers for Disease Control lists colonialism, poverty, and inadequate access to healthy foods, among other things, as key factors contributing to this disparity. However, if polygenic embryo selection continues to be less effective for Pacific Islander Americans, then this community could one day have systematically higher genetic risk for chronic health conditions than White Americans with European genetic ancestry, further worsening existing health disparities between Pacific Islander Americans and White Americans.

Imagine a similar dynamic playing out in educational settings. Today, children from working-class families are nearly twice as likely to not graduate from high school compared with children from upper-class families. Imagine how this disparity would grow if upper-class families (but not working-class families) were able to afford and utilize polygenic embryo selection to decrease the rate that their children suffered from learning disabilities, such as dyslexia and ADHD. Existing educational disparities between upper-class and lower-class American children would only worsen with disparate access to polygenic technologies.

Perhaps most concerning, if unequal access to embryo selection were to create class or racial disparities in genetic risk, then these differences would be passed onto future generations — potentially even compounding and accumulating over time. Richard Herrnstein and Charles Murray were dead wrong in 1994 when they wrote in "The Bell Curve" that genetic differences have naturally emerged between the American rich and poor or between White and Black Americans.

However, if care is not exercised, genetic differences between groups of people may emerge artificially through technologies like polygenic embryo selection. Troublingly, even the inaccurate and ineffective polygenic embryo selection that is occurring in the United States right now could spur the formation of new myths about group differences in genetic risk. The outsized power of genetic myths highlights how even just the perception that polygenic embryo selection has produced genetic differences between groups could become a problem in and of itself. In other words, if people believe that children born via polygenic embryo selection are materially dif­ferent from (or better than) children born without it, they may treat them differently — regardless of whether an actual difference exists. Scholars have shown that people can use the idea of genetic difference to disguise underlying racist, classist, and sexist attitudes.

Though concerns about polygenic embryo selection abound, it is important to also consider the potential upsides. Remember Sam's experiences with nerve damage and chronic pain from the previous chapter? A person's risk for chronic pain is meaningfully influenced by their DNA, and Sam's mom, Nina, has also suffered from sometimes debilitating chronic pain for most of her life. Being in pain is not a relative trait; one person hurting less is not inherently accompanied by another person hurting more. In a world where polygenic scores are accurate for individuals across the entire Family Tree, polygenic embryo selection could help reduce the rate of chronic pain in future generations. In such a world, Sam would have a hard time justifying a policy that prevented parents from accessing such a technology (and would even consider using it himself). The looming challenge is figuring out for which traits and under what circumstances polygenic embryo selection is and is not permissible.