Explore the fascinating world of behavioral genetics and biology: how genes, brain wiring and environment combine to shape intelligence, behavior and even trauma. Learn about heritability estimates, genome wide studies and the missing heritability problem.
Do we inherit behavior, intelligence or maybe trauma from our parents? Let’s find out
Have you ever wondered whether you’re acting like your parent because you learned it — or because you inherited it? In other words: do we inherit behavior, intelligence, or even trauma from our parents? The short answer is: yes — but it’s far more complex than just “you got their genes”. Let’s dive into behavioral genetics and biology to unpack what science has found.
Studies on heritability: big sample sizes, different countries
There have been many studies around the world (in different countries, large sample sizes) exploring how much of behavior and intelligence is inherited. Twin studies, adoption studies and even genome-wide association studies (GWAS) have been used. These large samples provide data on heritability — the portion of variation in a trait in a population that can be attributed to genetic differences.
However, studying humans has a catch: unlike lab rats, you cannot control all the environmental variables. Humans aren’t raised in identical cages with identical diets and stimuli, so while these studies are powerful, they have important caveats.
Heritability of behavior and intelligence: what’s the number?
When it comes to intelligence, many behavioural-genetics studies suggest heritability in the ballpark of 20–80%. That’s a large range — it tells us intelligence is substantially heritable, but it also tells us that a lot is due to “other stuff” (environment, experience, gene-environment interplay). So yes: genes matter. But they’re not the full story.
But it’s not simple — our parents don’t just pass down “intelligence genes” like some monogenic traits
When people hear that intelligence or behaviour is “heritable”, they sometimes assume “my parents had a high IQ so I must have the high-IQ gene(s) and that’s it”. That’s where things get misleading. Everyone has a brain, and the brain’s structure, wiring, and neural circuitry matter a lot in behaviour and intelligence.
Let’s break it down: neurons are the functional components of the brain — their wiring, firing and connections underpin how we think and behave. So what if I told you that your neural circuits might be somewhat similar to those of your parents? That the genes encoding brain development might produce roughly similar region-sizes in your brain for certain behaviours or emotions, and that your neural wiring might resemble that of your parents in broad strokes? That helps explain part of the “inheritance” of behaviour/intelligence. Due to the similar circuitry you might make similar inferences of the observations, that ultimately influences your behavior and intelligence.
But: this is not like a single gene for “being smart” or “being anxious”. Much more complex. Behaviour and intelligence are polygenic (many genes) and multifactorial (lots of environment, brain wiring, experiences).
From classic heritability studies to genome-wide association studies
In the early days of behaviour genetics, researchers used twin studies (monozygotic vs dizygotic twins) or adoption studies to estimate phenotype-based heritability (how much observable traits correlate among relatives). More recently, with whole genome sequencing and GWAS, researchers have tried to map the specific genes or variants associated with traits like behaviour or intelligence. For example, one paper on intelligence found that using common SNP markers accounted for ~40–50% of variation in crystallized/fluid intelligence — a lower bound for “narrow-sense heritability”.
But when you compare heritability estimates from classic twin-studies vs genome-wide studies, things don’t line up perfectly. This mismatch gives rise to the so-called “missing heritability” problem — we know traits are heritable (from twin studies), but we still don’t exactly know which genes, which combinations, which interactions, and which environmental modifiers explain that heritability.
What makes the inheritance of behaviour/intelligence so complex?
Many reasons.
First: gene interactions and regulation. We might know many human genes, but many genes can mask others, or interact in ways we don’t yet fully understand (gene-gene interaction, epistasis).
Second: epigenetic and environmental effects — how genes are turned on/off, how environments influence development, and how early life (trauma, stress, nutrition) affects brain wiring.
Third: brain structure and neural circuitry. Even though your parent’s genes may produce a brain region of a certain size or wiring pattern, your experiences, learning, and environment will shape how that circuitry is used, modified, strengthened or weakened.
Fourth: gene-environment interplay. Genes can influence which environments we seek out, how we respond to them, and environments can influence gene expression.
So what does this all mean for inheriting behaviour, intelligence or trauma?
Putting this all together: yes, your parents’ genes contribute to your brain wiring, your potential for certain behaviours, your intelligence, and yes, even predispositions to reaction patterns (which might look a bit like trauma transmission). But: your genes are just a starting point. How your brain develops, what circuits are formed, how early life goes, what the environment presents you, how you respond, all shape the final outcome.
Also: because the brain wiring (neural circuits) may resemble that of your parent to some degree, you may perceive the world in similar ways, react similarly, or have similar behavioural inclinations — but that doesn’t mean you are predetermined. Your environment, experiences, choices and internal changes matter a lot.
Conclusion
In the debate of nature vs nurture, behavioural genetics and biology show us that nature (genes) absolutely matters — but nurture (environment, experience, brain wiring) is equally essential. We inherit more than just physical traits — genes also pass down neural blueprints, cognitive tendencies, and subtle predispositions that can influence how we think, feel, and behave. But we do not inherit a fixed package that determines exactly how intelligent we’ll be, how we’ll behave, or how trauma will impact us. The story is nuanced: many genes, many interactions, many environmental modifiers make the final outcome. Understanding behaviour and intelligence means understanding genes, neuroscience, environment and how they all dance together. So while you may share some wiring with your parents, you’re still very much writing your own story.
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