Why We Respond Differently to Our Environments
A quiet revolution in science is changing how we think about genes, environment, and human nature.
Imagine two children growing up in the same household, experiencing what seems to be identical parenting. One emerges relatively unscathed from family difficulties, while the other carries lasting emotional scars. For decades, science struggled to explain such variations. The answer, we're now discovering, lies not in our genes or environment alone, but in their intricate dance—a concept known as differential susceptibility to context.
This article explores how this model is transforming our understanding of human development and why it matters for how we parent, educate, and support one another.
For much of the twentieth century, the nature versus nurture debate dominated discussions of human development. Behavioral genetics studies, particularly those involving twins, suggested that genes accounted for 30-50% of variations in everything from political preferences to schizophrenia risk 1 . These findings often left social scientists uneasy, as they seemed to diminish the importance of environmental factors like parenting and education.
The paradigm began to shift with advances in molecular genetics and the mapping of the human genome. Researchers discovered that many genes once thought to have powerful direct effects instead seemed to moderate environmental influences 1 . The genetic variable, unlike the environmental variable, often had little if any main effect on the outcome of interest. Rather, its influence was largely through its moderation of environmental effects 1 .
This recognition gave birth to the study of gene-environment interactions (GxE), which explores how genetic makeup influences our responses to different environmental conditions.
As Jay Belsky, a pioneering researcher in this area, theorized from an evolutionary perspective, children—even within the same family—should vary in their susceptibility to both adverse and beneficial rearing influences 7 .
To understand the significance of differential susceptibility, we must distinguish it from the earlier diathesis-stress model that long dominated psychological research 3 . Both models acknowledge that people respond differently to environmental challenges, but they tell strikingly different stories about who is affected and how.
The traditional diathesis-stress perspective suggests that some "vulnerable" individuals are disproportionately likely to develop problems when exposed to negative environments, while "resilient" individuals remain relatively unaffected across conditions 3 .
In this model, the vulnerable fare worse in adverse conditions but don't necessarily benefit more positively in supportive environments.
Differential susceptibility tells a more nuanced story. Those who appear "vulnerable" are not just more likely to struggle in adverse conditions—they're also more likely to thrive in positive conditions 3 7 .
Their susceptibility operates in both directions, "for better and for worse."
| Feature | Diathesis-Stress Model | Differential Susceptibility Model |
|---|---|---|
| Core Idea | Some "vulnerable" individuals are disproportionately affected by negative environments | Some "susceptible" individuals are disproportionately affected by both negative AND positive environments |
| Response Pattern | Unidirectional (worse outcomes in bad environments) | Bidirectional (worse outcomes in bad environments, better outcomes in good environments) |
| Terminology | "Vulnerable" vs. "Resilient" individuals | "Susceptible/Plastic" vs. "Less Susceptible" individuals |
| Evolutionary Rationale | Not explicitly evolutionary | Bet-hedging strategy for uncertain futures |
| Implications | Identify and protect vulnerable individuals | Identify and support susceptible individuals with positive environments |
From an evolutionary perspective, differential susceptibility represents what biologists call a "bet-hedging" strategy 3 7 . Ancestral parents couldn't know which childrearing approaches would prove most successful in promoting their children's survival and reproduction. Natural selection might have shaped parents to bear children varying in plasticity, ensuring that if a particular parenting style proved counterproductive, not all children would be adversely affected 3 .
In this evolutionary context, having both highly susceptible children (orchids) and less susceptible children (dandelions) within the same family provided a reproductive advantage. The dandelions' resilience ensured some offspring would survive across diverse conditions, while the orchids' sensitivity meant they might thrive exceptionally well if their specific environment matched their needs 7 .
These factors don't operate in isolation but interact in complex ways to shape an individual's responsiveness to their environment.
A groundbreaking 2025 study published in Frontiers in Psychiatry provides a compelling example of differential susceptibility in action 4 . Researchers investigated how two specific genetic variations—in the 5-HTTLPR and MAOA genes—interact with parenting quality to influence decision-making under risk.
264 young adults (aged 18-22)
5-HTTLPR and MAOA gene variants
Iowa Gambling Task (IGT)
The results revealed a clear differential susceptibility pattern, particularly among males. Those carrying the more sensitive variants of either the 5-HTTLPR or MAOA genes showed significantly better decision-making when they had experienced positive parenting, but worse decision-making when parenting had been less positive 4 . In contrast, individuals with the less sensitive genetic variants showed minimal fluctuations in performance based on parenting quality.
| Genetic Profile | Positive Parenting Mean Net Score (trials 61-100) | Less Positive Parenting Mean Net Score (trials 61-100) | Susceptibility Pattern |
|---|---|---|---|
| 5-HTTLPR SS/SL carriers | +8.3 | -5.7 | Differential Susceptibility |
| 5-HTTLPR LL carriers | +2.1 | +1.9 | Low Sensitivity |
| MAOA S-allele carriers | +7.9 | -4.8 | Differential Susceptibility |
| MAOA L-allele carriers | +2.3 | +1.7 | Low Sensitivity |
Research on differential susceptibility employs sophisticated methods and measures to unravel the complex interplay between genes and environment. The 2025 study exemplifies several key components essential to this field.
| Research Component | Function/Description | Application in the Featured Study |
|---|---|---|
| Genetic Genotyping | Identifying specific variations in DNA sequences | Analyzed 5-HTTLPR (serotonin transporter) and MAOA (monoamine oxidase A) gene variants 4 |
| Iowa Gambling Task (IGT) | Measures decision-making under uncertainty through card selection task | Assessed participants' decision-making quality across 100 trials 4 |
| Environmental Assessment | Quantifies quality of early environment through parent reports | Evaluated positive parenting styles and early life stress 4 |
| Polygenic Risk Scores | Combined measure of multiple genetic variants | Not used in this study, but employed in newer research to capture cumulative genetic sensitivity 8 |
| Experience Sampling Method | Repeated real-time assessment of experiences and responses in daily life | Not used here, but employed in other studies to measure momentary responses to environmental cues 8 |
The implications of differential susceptibility extend far beyond academic interest, touching multiple domains of society.
Understanding differential susceptibility can help parents and educators recognize that children who seem "difficult" or "sensitive" may actually possess a neurobiological sensitivity that represents both vulnerability and potential 7 .
Rather than viewing these children as problematic, we can create environments that allow their sensitivity to become an asset rather than a liability.
Educational approaches might be tailored to recognize that the same children who struggle most in chaotic classrooms may thrive exceptionally well in structured, supportive learning environments 7 .
The differential susceptibility model offers hope for intervention strategies. If the individuals most vulnerable to negative environments are also most responsive to positive changes, then interventions targeting these "susceptible" individuals should yield particularly strong returns 7 .
Research already shows that children with genetic susceptibility markers or difficult temperaments often benefit most from supportive parenting interventions 7 9 .
As research progresses, scientists are developing more comprehensive measures of environmental sensitivity, including polygenic sensitivity scores that combine multiple genetic markers 8 . Future studies will need to address important unanswered questions, such as how susceptibility changes across the lifespan and how cultural factors influence these patterns .
The science of differential susceptibility represents a paradigm shift in how we think about human development. It moves us beyond simplistic nature-versus-nurture debates and reframes what we previously considered "vulnerabilities" as potential strengths under the right conditions.
This perspective doesn't diminish the importance of environment but rather highlights that environments affect individuals differently.
Perhaps most importantly, this research carries a message of hope and responsibility. It suggests that creating nurturing environments—whether in homes, schools, or communities—isn't just about preventing problems but about unlocking human potential, especially for those most sensitive to their surroundings. The orchid children among us, who might seem most vulnerable to adversity, may possess the greatest capacity to flourish when given the support they need.