Schizophrenia is one of the most heritable conditions nobody screens for
Parents who ask us about schizophrenia screening have usually been thinking about it for a long time. They’ve watched a father lose a job, a sister stop calling, a son move back home in his twenties. They know what it look like living with the disease, because they've already been there when it happened to someone they love.
When more than one family member is afflicted, they probably also understand that schizophrenia is heritable. With one affected parent, a child's lifetime risk is around 10%. With an affected sibling, about the same. With an identical twin, closer to a third.
What most people don’t know is that schizophrenia is one of the most heritable conditions in all of medicine. It is more heritable than breast cancer, type 2 diabetes, and coronary artery disease. The Danish Twin Register shows that schizophrenia is highly heritable. Nevertheless, no IVF clinic in the world routinely offers to screen embryos for it.
The science is there, but IVF doctors do not take advanced genetics classes, nor do they tend to keep up with the latest research in human genetics. IVF most IVF doctors don’t offer schizophrenia testing because they don’t know that it exists.
A strong signal
A heritability estimate is the share of variation in who develops a condition that can be chalked up to genetic differences rather than environmental ones. For schizophrenia, that share has been stable across studies and decades. Hilker's Danish cohort landed at 79%. A meta-analysis of twelve twin studies by Sullivan, Kendler, and Neale put it at 81%, with a confidence interval of 73 to 90%. The shared environmental contribution, the part that parenting, neighborhood, and family stress can explain, came in around 11%.
That's a strong genetic signal:among the strongest in clinical medicine.
The genetic architecture is also well-mapped. The largest schizophrenia GWAS to date, published in Nature by Trubetskoy and colleagues, combined 76,755 cases with 243,649 controls and identified 287 genome-wide significant loci. Common variants account for about 25% of overall risk, concentrated in genes that govern how neurons form synapses and pass signals. This is a condition caused by many small genetic variants, each one adding up to an overall lifetime risk.
But the question that matters for IVF isn't whether polygenic scores predict schizophrenia risk in the general population. It's whether they predict differences in risk between embryos that share the same two parents. Embryos from an IVF cycle are biologically siblings, and siblings are more genetically similar to each other than strangers are. So the validation that counts is the one done on siblings, not on unrelated people from a biobank.
That's the test Moore et al. 2025 ran. Schizophrenia was one of the 17 disease scores checked in the sibling context. Sixteen of seventeen showed no drop in predictive performance within families. The schizophrenia score held up.
What the number on the report actually does
Polygenic embryo screening doesn't tell you which embryo will develop schizophrenia and which won't. Almost no genetic test does that, since most individual genes do not determine outcomes, but instead alter probabilities. Polygenic risk scores simply allow parents to see which embryos carry higher or lower genetic predisposition than the others.
The variance polygenic scores explain for schizophrenia is lower than what they explain for metabolic conditions like diabetes or heart disease. In the Moore et al validation, schizophrenia's liability R² came in around 10%.
That's useful because the reader of this article is almost never at the general-population baseline. A family with one affected parent is already looking at about 10% risk, not 1%. A family with an affected sibling sits in the same neighborhood. At those elevated baselines, even a modest polygenic shift translates to a real absolute change.
Most polygenic scores were built from European and Asian ancestry data, so our polygenic scores decline in predictive power for some groups. . Nevertheless, screening works for every family who needs it, especially when there is a family history of a specific disease, even if the benefits are uneven across ethnic groups.
The creativity argument
Families who have lived with schizophrenia sometimes hear that screening against it might screen against artistic temperament. The argument comes from a real observation. Relatives of people with schizophrenia are overrepresented in creative professions. There's a modest shared signal with bipolar disorder too, with a cross-disorder genetic correlation of about 0.7, and both conditions have been linked to creative fields.
But a crucial point is often overlooked. The relatives show overrepresentation in the creative professions. The people with the clinical disorder don't. A meta-analysis by Acar and colleagues actually found a negative correlation between schizophrenia and creative achievement, r around minus 0.32. Severe psychosis isn't a productive burst of ideas. It's delusions, disorganized thinking, often a decade or more of lost functioning.
The variants that drive risk for the clinical disorder and the variants that underlie creative temperament in unaffected relatives aren't the same genetic signal. Screening reports the probability of the clinical condition. It doesn't screen out personality.
Families who have watched schizophrenia up close already know the difference between a vivid imagination and a full break with reality. They don't need anyone to explain it.
A gap the science can't close on its own
The heritability has been understood for decades. The GWAS has mapped hundreds of loci. The within-family validation has been run. What's missing is a profession trained to bring those results to the families who would use them, and that's the gap Herasight was built to close.
If schizophrenia runs in your family and you're thinking through IVF, our counselors can walk you through what the screening shows for your specific situation. Please reach out to us.