What Counts as Disease? Embryo Screening and the Ethics of Genomic Selection
- Daniel Kiss
- 5 hours ago
- 8 min read
As genomic technologies move from treating disease to selecting future individuals, definitions of disease cease to function exclusively as medical categories and become social decisions about which traits and what kinds of people should exist.
There is a quiet assumption embedded in much of genomic and reproductive medicine, particularly in industry-driven environments: that we know what a disease is.
Most of the time, we take this for granted. Diseases are conditions that negatively impact an individual's physical or mental wellbeing, and, more often than not, make life harder. They can be diagnosed, classified, and, where possible, prevented or treated by identifying underlying biology. In the context of embryo selection or gene editing, the logic seems even cleaner: identify harmful mutations, reduce risk, improve lives.
However, as genomic technologies are increasingly applied within reproductive contexts, this assumption begins to break down. The question is no longer just about whether we can select against certain genetic predispositions, but which of these predispositions are worth selecting against.
More specifically, genomic medicine begins to rely on a definition of “disease” that is far less biologically fixed and far more dependent on social context, interpretation, as well as individual and collective values. As genomic technologies move from treating illness to selecting future individuals that are more or less likely to develop certain traits, definitions of disease cease to function exclusively as medical categories and become social decisions about which traits and what kinds of people should exist.
Disease is Not Just Biology
In clinical genetics, disease is often framed as a deviation from normal biological function caused by identifiable mutations, a model that holds reasonably well for certain conditions. Single-gene disorders like cystic fibrosis or Tay–Sachs have relatively clear causes and predictable clinical outcomes, allowing them to fit more comfortably within a biological model of disease.
Nonetheless, even in cases where there is a clear genetic basis for disease, the boundaries may still be less precise than they appear. The manifestation of an undesirable genetic condition is often dependent on environmental conditions, access to healthcare, and interactions with other genetic factors. In this sense, two individuals with the same disease-causing mutations can live radically different lives with significantly different disease symptoms. What looks like a discrete biological category is, in practice, probabilistic and context-dependent.
This tension is not unique to genomics. Medical definitions of disease have always shifted alongside social norms and cultural values. Conditions once framed as pathological, including homosexuality and various forms of neurodivergence, have since been reevaluated through changing social and scientific perspectives. Reproductive genomics does not create this problem, but it does intensify it by integrating social classifications of illness into reproductive decisions without proper due diligence.
This instability becomes even more pronounced when considering the number of factors that play a role in the manifestation of complex traits such as cardiovascular disease, diabetes, or psychiatric conditions. Current prenatal screening methods make use of polygenic scoring, which is not used to diagnose disease, but rather to estimate the relative health risks within a population. The use of polygenic scoring in reproductive medicine can determine whether an embryo will have a relatively higher or lower disease risk compared to others, but not whether it will eventually develop the condition.
Here, we are no longer selecting against a defined disease outcome, but between a number of statistical futures. This raises a problem: when risk becomes continuous rather than discrete, where do we draw the line between what we consider to be a disease versus a trait?
Disease as a Social Construct
Biology alone doesn’t determine whether something is experienced as harmful. Social and environmental contexts play a significant role in shaping how traits are interpreted and whether they are deemed to be "normal".
Consider congenital deafness. Within clinical frameworks, it is often classified as a sensory impairment, while within Deaf communities it may also be understood as a cultural and linguistic identity. These perspectives are not necessarily in conflict, but they reflect fundamentally different ways of interpreting the same biological condition.
Similar considerations apply to neurological traits, including autism spectrum disorder and ADHD, where the degree to which these traits are experienced as disabling depends in part on how environments are structured, what is accommodated, and what is stigmatized. In each case, the label of “disease” or “disorder” is not rooted in biology but instead, reflects social norms and collective values.
In this sense, what counts as disease is shaped not only by biology, but by the conditions under which that biology is expressed. If the impact of a trait can be mitigated through social or technological means, it becomes less clear that it should be treated as something to eradicate.
The Non-Identity Problem and the Ethics of Genomic Selection
Even if we were able to clearly define disease in biological or social terms, reproductive genomics introduces a further ethical complication that distinguishes it from conventional medicine. In most healthcare contexts, treatments are consented to by patients seeking to alleviate symptoms or improve their quality of life. Embryo selection operates under a fundamentally different logic, as there is no patient in the traditional sense.
The Non-Identity Problem, most famously articulated by philosopher Derek Parfit, challenges the idea that selecting one embryo over another can be understood as “preventing harm.” Selecting one embryo over another does not alter the life trajectory of a particular individual, but instead determines which individual will come into existence. As a result, the concept of preventing harm becomes difficult to apply in its conventional form. Using embryo selection to reduce the likelihood that a future child will have a particular condition does not benefit that child in the conventional sense, since the alternative would have been the existence of a different individual.
This complicates a common justification for embryo selection: that it benefits the future child. Instead, embryo selection may be better understood as shaping which kinds of people exist, rather than improving the welfare of a specific individual.
Some critics, most notably bioethicist Julian Savulescu who coined the term Procreative Beneficence, argue that parents may have a moral obligation to select embryos expected to lead to the “best” possible life. From this perspective, embryo selection is ethically justified even if it does not explicitly benefit a future child, but because it increases the likelihood of producing the child with the greatest expected wellbeing.
However, this framework depends heavily on assumptions about what constitutes a good life, which are in and of themselves socially constructed beyond certain universally-agreed-upon definitions of harm. As reproductive genomics moves towards the perturbation of increasingly complex traits, these judgments become more difficult to separate from social norms, cultural preferences, and existing systems of inequality.
The Problem with Complex Traits
These questions become even more complex when applied to polygenic traits. Unlike single-gene disorders, traits like depression, obesity, or intelligence are influenced by thousands of genetic variants, each contributing a small effect. They are also shaped by the environmental, socioeconomic, and stochastic factors.
Polygenic screening can rank embryos by relative likelihood of developing a trait. The challenge is that many of these traits exist on a spectrum between what can be considered to be natural variation within a population and what can be considered debilitating and harmful. For example, genetic predisposition to depression is associated with an increased risk of suffering, but the underlying genetics are also associated with culturally sought-after traits such as creativity and emotional sensitivity.
Interventions aimed at reducing the risk of such traits are often framed as therapeutic, yet the same methodologies can be extended to characteristics that are not traditionally considered pathological, including height, athleticism, cognitive ability, or personality. As traits become more complex, the distinction between disease and preference becomes increasingly difficult to maintain, and decisions that appear clinical begin to take on aesthetic or value-driven dimensions.
Individual Choices, Collective Outcomes
There is also a broader societal dimension to consider. Technology does not exist in a vacuum. It is shaped by economic incentives, cultural norms, and systems of power. In many cases, once a technology becomes available, it becomes hard to resist. This is particularly true in highly commercialized reproductive and fertility industries, where clinics and biotechnology companies compete by offering increasingly comprehensive forms of screening and optimization. In these contexts, technologies are not medical tools as much as they are consumer products shaped by market incentives and parental anxieties surrounding health, success, and social mobility.
Prenatal screening for conditions such as Down syndrome provides a clear example, having led to significant reductions in the number of children born with the condition in many regions. These outcomes have not been driven by explicit policy, but rather by the combined effect of individual decisions within a framework that implicitly defines certain traits as undesirable.
As embryo screening technologies expand, similar patterns may emerge across a wider range of traits. What begins as a niche option may gradually become an expectation, particularly in systems and industries driven by optimization, competition, and risk minimization. Over time, this may narrow the range of traits considered acceptable, reinforcing existing social norms under the appearance of individual choice. Thus, it can be argued that it is never truly possible to separate individual decisions from the social contexts and pressured in which they exist.
In this sense, the ethical concern is not primarily about coercion, but normalization. Even in the absence of regulatory oversight, systems built around individual choice can still produce collective pressures that shape which forms of human variation become more commonplace. The question, therefore, is not only what individuals choose, but how those choices are shaped by the environments in which they are made.
Beyond “Playing God”
Discussions of embryo editing and ethics of genomic selection often invoke the idea of “playing God.” While this framing captures a sense of unease, it risks oversimplifying what is actually at stake. The challenge is not that humans are crossing a natural boundary, but that values and ideas that are deeply intrenched in social and economic pressures are being framed as decisions made independently by individuals. This process is iterative, with future generations themselves being influenced to select against traits that are lie outside the distribution of a continually shifting definition of health. The result, is a trajectory presented as the consequence of individual liberty, but in reality, is a social pressure affecting the kinds of individuals we deem are allowed to exist.
What counts as a life worth living? Which traits should be avoided, and which should be preserved? These are not questions that can be resolved through scientific evidence alone, but instead reflect deeper ethical, cultural, and political judgments about what we value, both as individuals and as a collective.
These concerns also inevitably invite comparisons to historical eugenic movements, though contemporary reproductive genomics differs in important ways, particularly in its emphasis on individual choice rather than overt state coercion. Nevertheless, both contexts raise similar questions about which forms of human variation are considered desirable, acceptable, or worth preventing.
What Is the “Right” Way Forward?
The concept of disease occupies a central role in genomic medicine, yet it does not have a purely biological definition. It would be easy to frame this as a binary: embrace these technologies or reject them, but that framing misses the point.
The challenge is not simply whether we can shape the health outcomes of the next generation, but whether we are prepared to define, collectively, what kinds of difference are worth preserving. If left unexamined, the assumptions embedded in current technological practices may lead to a narrowing of our understanding of what constitutes a healthy individual, our definitions of health and harm, and what it means to live a good life.
Ultimately, the central question is not only who gets access to these technologies, but who gets to define disease itself, and whose values become embedded within systems of genomic selection and optimization. As the boundary between disease and difference continues to blur, the decisions made today will shape not only future individuals, but the range of human diversity that future generations inherit.
Daniel Kiss is a Research Associate at Genomics4S, where he supports research projects in science policy and genomics and contributes to public outreach initiatives.