Are you dreaming of a child who's not just healthy, but exceptionally tall and brilliant? For many hopeful parents navigating the world of IVF, the promise of genetic testing offers a tantalizing glimpse into that future. Companies are now marketing sophisticated tests that claim to predict which IVF embryo holds the genetic blueprint for your child's ultimate height, intelligence, and overall health. It sounds like science fiction, doesn't it? But here's where the dream starts to encounter a harsh reality.
The stark truth is, these cutting-edge tests, while sophisticated, cannot reliably deliver on their grand promises. The purported benefits are likely to be incredibly small, almost negligible, while the potential risks to patients, the children born from these selections, and society as a whole are very real and significant. Parents embarking on this journey deserve clear, accurate information, not just marketing hype, especially when making such monumental decisions about their future family.
So, what exactly are these tests, and how do they work?
Currently, IVF patients can opt for genetic testing to screen embryos for serious inherited conditions, like cystic fibrosis, which are often linked to a single gene. However, the new wave of testing goes much further. It attempts to predict complex traits that are influenced by thousands of genes working in concert. These advanced tests generate what are known as “polygenic risk scores” for each individual embryo. Essentially, this score represents an embryo's theoretical likelihood of developing certain conditions, such as heart disease or Alzheimer's, or exhibiting specific traits like a high IQ or above-average height. Armed with this information, parents can then choose which embryo or embryos to proceed with. While these tests aren't yet offered by Australian companies, several US-based firms are actively marketing them. One company, for instance, has plastered New York with advertisements proclaiming, “Have your best baby,” and offers to screen embryos for an astonishing 2,000 traits, ranging from eye color and IQ to the likelihood of baldness and the predisposition to conditions that typically manifest later in life, like Alzheimer's and heart disease.
But what does the actual scientific research tell us?
Our research group took a close look at whether this technology is truly ready for widespread clinical use. We evaluated the effectiveness of using polygenic risk scores for embryo selection, applying the same rigorous framework used to assess any medical screening test. Our findings were clear: these predictions are fraught with extreme uncertainty. For starters, researchers can't even begin to assess the benefits of predicting late-onset diseases because the outcomes won't be known for decades. Mathematical modeling suggests the benefits are vanishingly small – perhaps an increase of only a few IQ points or 1-3 centimeters in height. While 3cm might sound like a significant difference to some, we can't be certain about its relevance, or the relevance of other predicted benefits, for several critical reasons.
And this is the part most people miss: Polygenic risk scores have been developed by studying individuals currently in their 50s and 60s, people who grew up in vastly different environments. Imagine their lives without smartphones, without the current prevalence of processed foods, and with different levels of air pollution and microplastic exposure. Their educational systems, healthcare access, and lifestyle choices were fundamentally distinct from ours today. This historical context is crucial because traits and diseases aren't just about genes; they're the result of a lifelong interplay between our genes and our environment. The very same genetic variations that might have contributed to diabetes in the 1960s could behave very differently in today's world. Therefore, we cannot assume that genetic patterns observed in past populations will accurately predict outcomes in our radically transformed future environments.
Here's where it gets controversial: Lifestyle and environmental factors are incredibly powerful influencers on our development, and genetic testing simply cannot capture them. Polygenic risk scores, by their nature, only examine one side of a very complex equation, completely ignoring the environmental side, which may be just as, if not more, important. Take IQ, for example. Early childhood education, nutrition, parental involvement, and socioeconomic status all have an enormous impact on cognitive development. Choosing an embryo based on a marginally “better” genetic score for IQ, while overlooking these well-established influences, is akin to trying to predict a plant's height solely from its seed, without considering the quality of the soil, the amount of sunlight, or the availability of water.
Furthermore, there's a phenomenon called pleiotropy, where a single gene can influence multiple traits. This means that selecting for a desirable trait, like higher educational achievement, could inadvertently increase your embryo's risk of developing a condition like bipolar disorder. It's a complex web of genetic interactions that we are only beginning to understand.
So many issues and concerns arise from this technology.
In Australia, national guidelines recommend preimplantation genetic testing primarily to prevent serious genetic conditions. However, polygenic risk scores are designed to predict the future risk of developing a condition or trait, not to diagnose a current condition. This distinction means that using polygenic risk scores for embryo selection goes against current guidelines and operates in a regulatory grey zone. Despite this, prospective parents, even from Australia, are sending genetic samples or information derived from them overseas for analysis.
Beyond the regulatory landscape, there are profound ethical concerns. This technology bears an unsettling resemblance to eugenics movements of the past, which led to horrific outcomes like forced sterilization and atrocities. Selecting embryos based on traits like intelligence or skin color risks reinforcing existing discrimination and widening social inequalities. But here's where it gets even more complicated: Many parents face “decision paralysis.” When presented with polygenic risk scores for multiple embryos, detailing risks for dozens of conditions and traits – from breast cancer and heart disease to schizophrenia, higher IQ, and height – how does one possibly make a choice? These aren't simple medical decisions; they are impossible value judgments. Parents can become overwhelmed, second-guessing their choices for years, or even deciding not to transfer any embryos at all.
There’s a cruel irony at play here: couples who opt for IVF solely for polygenic risk score testing, rather than for fertility issues, may actually reduce their chances of having a healthy baby. IVF itself carries risks, including an increased chance of high blood pressure during pregnancy and preterm delivery. Moreover, the very act of obtaining a biopsy from an embryo to analyze its DNA could potentially impact pregnancy outcomes. So, in their quest for unproven benefits, prospective parents might be exposing themselves and their potential children to proven risks.
What’s the take-home message?
The “best” child isn't defined by the highest genetic score. Instead, it's a child born into a loving family, with access to good nutrition, quality education, and excellent healthcare. These environmental factors wield far greater influence over a child's development than any minor variations in their DNA.
I'd like to acknowledge Dr. Genia Rozen from the University of Melbourne, who was a co-author on our research and contributed significantly to this article. What are your thoughts on using genetic testing to select embryos for non-medical traits? Do you believe the potential benefits outweigh the ethical concerns and the uncertainties?
