There is broad scientific consensus that intelligence is partly inherited and that genes play a significant role. But pinning this incredibly complex trait down to precise contributions of specific genes is a far more thorny scientific challenge—and claims that it can produce significant IQ “gains” in the context of embryo screening are widely considered controversial.
Despite the science being uncertain, it has emerged that at least one company, US startup Heliospect, is preparing to publicly launch a service that allows parents who have conceived multiple embryos through IVF to selecting those most likely to have “desirable” characteristics. , such as height and IQ.
Complex traits, such as IQ, are not determined by a single mutation, but are influenced by the small contributions of thousands of genes that only became detectable with the advent of large genetic databases, such as UK Biobank.
The testing is done by taking samples of DNA and looking for patterns. In the case of an embryo, a few cells are extracted to provide DNA results, which a company like Heliospect will use through its prediction algorithm.
Scientists can use the data to look for statistical correlations between genes and a person’s educational attainment (sometimes used as an IQ proxy), risk of psychiatric disorders and a whole host of other traits.
The genetic contributions can be summed to give a so-called polygenic score. But these scores are based on probability, rather than being a guarantee. Environmental and random biological variation also play a role. An embryo with a mediocre score can turn out to be a genius, and vice versa.
And, in the broader context of society, access to health care, education and a supportive family environment can have as great an impact as inherited traits.
The company appears to have suggested that couples who use their service can expect to have a child who is, on average, six IQ points smarter than the child they would have had through natural conception. This is significantly higher than the 2.5 IQ point expected gain estimated in a 2019 study, which considered this hypothetical scenario. The validity of Heliospect’s claim is impossible to ascertain, although independent experts have expressed skepticism.
One issue is that genes linked to good parenting – genes that are also passed on to children – also contribute to academic outcomes. But these genes benefit a child by helping to provide a friendly, nurturing home environment rather than directly making them smarter.
Prof Hank Greely, of Stanford University in California, said he did not believe that studies so far demonstrated an ability to make genetic predictions of the future intelligence of embryos precisely enough to yield anything other than “insignificant” gains. “My first reaction is that it’s not real,” he said.
Even accepting the claimed six IQ point gain, this assumes that 10 embryos will translate into 10 viable pregnancies, which is not the reality for most couples. For women, aged 18-34, the average live birth rate per embryo transferred is 33%, according to figures from Human Fertilization & Embryology Authorityand it drops to less than 10% for women over 40. There is also attrition between eggs that are retrieved and embryos that are created. Many couples do not have 10 viable embryos to choose from and for others it will require an unusually intensive series of IVF cycles, which are not without risk.
Beyond possible medical risks, IQ screening of embryos raises a host of broader ethical questions. Some fear the technology could lead to a Gattaca-style stratified society. The 1997 science fiction film presented a world with a genetically enhanced upper class and a naturally born lower class.
Supporters of polygenic screening of embryos often cite the success of animal breeding schemes as evidence for the potentially significant benefits of trait selection. But others note that family tree programs can produce unexpected “riding along” effects. In one case, in the 2010s, scientists bred so-called “super chickens” after selecting successive generations of fertile egg layers in an effort to boost livestock productivity. But the superchickens also seem to be incredibly aggressive. When they were brought into a farmyard environment, the flock fell into disarray, with some of the hens pecking each other to death. There is no guarantee that selecting for high IQ in humans will not also produce unexpected outcomes.
