I keep finding myself in the same debate.
It comes up in the corridors of conferences, seminars, in the middle of lectures, when I ask a question that sounds innocent enough, and then suddenly everyone has an opinion. The question is always some variation of the same thing: how much of who you are was given to you and how much did you build?
Nature versus nurture. This is one of those debates that feels settled until it isn’t. I’ve seen students defend education with a kind of moral urgency, as if to say that genes matter as much as effort doesn’t. I’ve seen researchers argue for heritability estimates as others argue for politics: they certainly haven’t earned it.
I consider myself somewhere in the middle of it all, though not in the “both” way. I mean, he’s genuinely uncertain, genuinely curious, and increasingly convinced that the real story is stranger than either camp is admitting.
A study published in 2026 Scientific Reportsdrawing on data from the German TwinLife project, gave me new ideas. Not because he settled the debate, but because he took it in an interesting direction.
What the study actually found
The TwinLife project started after about 880 twins over several years. About half are identical twins (share all their DNA) and the rest are fraternal twins (share about half). Because both groups grew up in the same household, the researchers were able to distinguish how much of the differences between them came from genes and shared environments.
The participants took an IQ test at age 23. Four years later, their socioeconomic status was assessed based on education, occupation and income.
The main finding: At age 23, about 75 percent of IQ is genetically predicted. The relationship between intelligence quotient and socio-economic status is also largely genetic, varying between 69 and 98 percent depending on the measure.
This is a striking range.
The researchers were careful to note limitations: they did not directly control for parents’ IQ or socioeconomic status, and gene-environment interactions can inflate heritability estimates by as much as 15 percentage points. These caveats matter and I will return to them.
But even if we put the ceiling numbers aside, it’s worth considering the basic finding: genetics can influence not only intelligence, but also how much education shapes you. The “silver spoon”, as personality psychologist Petri Kajonius put it, “is not as big as you think. Your home life also depends on your genes”.
That last line stuck with me.
The part that people usually miss
Most of behavioral genetics focuses on direct effects: your genes influence your IQ, which influences outcomes. This is already a contested area. But the more interesting and less-discussed finding concerns the gene-environment correlation, which is the idea that your genes influence not only who you are, but also the environment you end up in.
This works in a few ways. Passive gene-environment correlation occurs when parents pass on genes and the environment at the same time. A parent with high verbal ability can pass on the genes for that ability and create a home full of books. The child benefits from both, but you cannot completely separate them.
The active gene-environment correlation is different. As we grow up, we increasingly select, shape, and create environments that match our genetic predispositions. Someone with a natural tendency to think abstractly seeks scientific connections. Someone with a strong social motivation gravitates towards high-contact environments. The environment reacts to people, not just the other way around.
This means that the environment does not act on you as a neutral force. You, shaped in part by your genes, seek out certain environments and not others.
Why the nature and nurture framework always fails us
I have had this conversation many times in a university setting. When you give high heritability estimates, the room often splits in predictable ways. One group hears that “genes determine everything, so intervention is futile.” Another group hears threats to beliefs about social mobility and bristles.
Both reactions miss the point.
Heredity is a population-level statistic. It tells how much of the variation in a given trait in a given population at a given time is explained by genetic differences. It doesn’t say anything about whether a property can change. Height is highly heritable, but average height has increased over generations due to nutrition. Heritability estimates remained high even despite the shift in the mean.
The same logic applies here. To say that IQ in this sample is 75 percent heritable does not mean that IQ is fixed or that environment is irrelevant. This means that within a given population living under these conditions, genetic differences account for more variation than environmental differences. Dramatically change the range of environments and this estimate may change.
The authors of the study acknowledge this. They note that targeted interventions can still help people succeed, and that the findings do not suggest that the environment is irrelevant, just that it may have limitations in “reshaping deeply rooted traits over time.”
This is a careful, honest position. It is also something that the popular formulation of the debate rarely makes room for.
What does this mean for our thinking about education?
Here’s the piece that’s really hard to sit with.
We tend to treat parenting and the family environment as primary inputs. The assumption embedded in a lot of psychology, a lot of parenting advice, and a lot of education policy is that if you create the right environment, you will get the right results. Bonding, stimulation, stability, opportunity: give children these things and you shape their path in a meaningful way.
This assumption is not exactly wrong. But it may be less complete than we thought.
If children actively choose and shape their own environment from an early age – partly through genetic predispositions – then the arrow of causality never points in just one direction. A child who shows an early interest in reading influences how much parents read to them. A child with high emotional sensitivity elicits more cautious and regulated reactions from caregivers. The “environment” is partly a product of what the child takes in.
It does not leave parents because of harmful behavior or deprivation. A harmful environment is still harmful regardless of what genes the child carries. But this complicates the idea that a good enough environment more or less reliably produces good enough results.
For parents reading such a study, Kajonius suggests that it can actually reduce anxiety. Many parents believe that their decisions determine their child’s future success. The data suggest that they have less control over long-term socioeconomic outcomes than previously thought. This is not nihilism. It’s a different kind of honesty.
The issue of social mobility
The study raises something it doesn’t fully resolve: If genetics strongly predicts life outcomes, what does that mean for policies aimed at increasing social mobility?
It is worth being careful here, because this is where science can be most easily misused.
High heritability does not mean that social mobility is impossible. That doesn’t mean we should stop investing in education or early intervention. This means being realistic about what these interventions can and cannot do, and being honest when the evidence shows limitations.
A policy aimed at leveling the environment may paradoxically increase heritability estimates over time. If everyone has access to the same quality of education, nutrition, and stability, the remaining variation in outcomes is attributable to genetic differences more, rather than less. An equal environment does not cancel out genetic influence; they just shift where the variation comes from.
This is not an argument against equality. This is an argument for being specific about what we want to achieve and what success would look like.
Where the debate is still really alive
I want to push one thing back before I go any further.
The TwinLife data are of German origin, from a relatively high socioeconomic range, and from a specific developmental window (early adulthood). Heritability estimates vary by population, time period, and lifetime. Some researchers argue that the heritability of cognitive abilities increases with age because people have more freedom to choose their own environment. Others find that socioeconomic extremes, whether poverty or affluence, significantly alter the expression of genetic potential.
The range of 69-98 percent genetic contribution to the IQ-SES relationship is also a wide range. That matters. If the confidence interval spans 30 percentage points, it does not give a close result; you describe something real, but inaccurately.
None of this means that the study is bad or not worth including. That means it’s a contribution to a conversation, not the end of it.
I’ve been in enough conference hallway debates to know that people on both sides tend to want more certainty than the data supports. The honest point is that genes matter more than many people care to admit, and environment matters more than some researchers are willing to emphasize, and the interplay between them is indeed complex, in ways that pure heredity numbers don’t capture.
Sovereign Mind lens
At Ideapod, we think about the ability to think independently through the so-called framework system The Sovereign Mind. It is built around three layers, all of which are applicable here in ways that are worth naming.
- Unlearning: The legacy script in this field is that your upbringing is the primary force that determines who you become. This belief creates a huge amount of parental angst, educational ideology, and self-recrimination. The research suggests that it should be relaxed, not abandoned entirely, but revisited with greater nuance than usual.
- Renovation: Understanding the gene-environment interaction returns some cognitive ability. When you stop looking for your own reason, you can be more honest about what is actually moldable and what isn’t. This clarity is a form of restoration of attentional and psychological resources.
- Protection: The nature vs. nurture debate is regularly diverted for ideological purposes, from genetic determinism at one end to blank-slate social engineering at the other. Knowing the actual state of the evidence protects you from either camp and from oversimplifying a pre-existing conclusion.
A final reflection
The nature vs. nurture debate is one of those arguments that will never be fully resolved, and I’ve come to believe that it’s not a failure of science, but a peculiarity of the question itself.
Human development is indeed complicated. Genes influence the environment. The environment determines the expression of genes. And people are active participants in the construction of their own psychological world from a very young age.
TwinLife’s findings are a useful corrective to a story that is a little too orderly. The “silver spoon” matters, but perhaps less so than the spoon he was born to reach for.
This is no reason for fatalism. It’s a reason to ask better questions and take the ones we think we’ve already answered a little more lightly.
