Attention‑deficit/hyperactivity disorder has long been described as a condition shaped by genes, family history, and early experience.

Yet lived reality often looks messier. Two children raised in the same household, exposed to the same routines, rules, and stresses, can develop in strikingly different ways. One child may struggle with focus, impulse control, and planning, while a sibling shows few signs of difficulty.

New research adds weight to the idea that this variation begins far earlier than most people assume, and that the seeds of difference may be visible within weeks of birth.

The study, published in Infant and Child Development, followed boys from infancy to early primary school. It suggests that early activity levels, measured at just one month of age, may signal how strongly a child responds to their surroundings.

For some infants, the home environment appears to matter more than for others, with effects that linger into the school years. The findings help to reframe ADHD risk, shifting attention away from simple cause and effect and towards a more dynamic picture of sensitivity and responsiveness.

ADHD is commonly understood as a neurodevelopmental condition with a strong genetic component. Family history remains one of the most robust predictors. Children with a parent who has ADHD symptoms face a higher likelihood of developing similar difficulties.

Yet genetics do not act in isolation. Environmental factors such as parenting style, emotional climate, and cognitive stimulation also shape development. What has been less clear is why some children seem deeply affected by these influences while others appear relatively unchanged.

For decades, much of the research focused on vulnerability. Children with inherited risk were thought to be especially harmed by chaotic or unsupportive environments. This view implied a one‑directional process. Bad environments worsen outcomes. Good environments merely reduce harm.

Over the past two decades, however, scientists have proposed a more nuanced framework. Known as differential susceptibility or vantage sensitivity, it suggests that some children are simply more open to environmental input of all kinds. These children may struggle more in adverse settings, yet thrive more in nurturing ones.

The new study builds on this idea by asking how early such sensitivity can be detected. Most previous research has identified environmental responsiveness in toddlers or older children, after years of experience have already accumulated.

By contrast, the research team focused on the neonatal period. Their goal was to see whether temperament measured at one month could shape the long‑term impact of the home environment on executive function, a set of cognitive skills closely linked to ADHD.

Executive function includes abilities such as sustaining attention, holding information in mind, switching tasks, and inhibiting impulsive responses. Difficulties in these areas often precede a formal ADHD diagnosis. They can influence learning, behaviour, and emotional regulation long before symptoms become clinically apparent.

Improving executive function is therefore seen as a key pathway for reducing later difficulties, even when ADHD symptoms themselves remain unchanged.

The researchers followed 95 boys from birth to the age of seven as part of an ongoing longitudinal programme in Israel. The sample was deliberately enriched for ADHD risk, with many parents reporting elevated symptoms themselves. This allowed the team to examine how child characteristics and parental traits interact over time.

At one month of age, mothers completed a well‑established questionnaire assessing infant temperament. The analysis focused on three broad dimensions. The first, known as surgency, reflects activity level, energy, and positive reactivity. Infants high in surgency tend to move more, show greater motor activity, and react strongly to stimulation. The second dimension, negative affectivity, captures tendencies towards distress, fearfulness, and irritability. The third relates to early regulatory capacities, such as self‑soothing and emerging attention control.

Several years later, when the children were aged four and a half, trained observers visited the families’ homes. They assessed the quality of the environment using a structured tool that measures learning materials, cognitive stimulation, emotional support, and parental involvement. At age seven, executive function was evaluated using a combination of computer‑based tasks and parent‑reported questionnaires. These measures were combined into a single composite score. Both parents also completed validated assessments of ADHD symptoms.

Statistical models accounted for factors such as child IQ, parental education, and age at testing. This helped to isolate the specific role of temperament and environment. The results were striking in their simplicity.

Of the three temperament traits measured in infancy, only surgency made a difference.

For children who had been highly active at one month, the quality of the home environment strongly predicted executive function at age seven. Those raised in more enriched, supportive, and stimulating homes showed markedly better executive skills. Those in less enriched settings showed poorer outcomes. In contrast, for infants with average or low levels of early activity, the home environment had little measurable effect on later executive function.

Parental ADHD symptoms intensified this pattern. Children who combined high neonatal surgency with parents reporting more ADHD symptoms were the most responsive to their surroundings.

In supportive homes, they performed particularly well. In less optimal environments, they struggled the most. This pattern fits closely with the idea of environmental sensitivity rather than simple vulnerability. The same trait that confers risk in one context may confer advantage in another.

Notably, other temperament traits did not show this moderating effect. Early fearfulness, distress, or emerging self‑regulation did not change how the home environment related to later executive function. Nor did the home environment directly predict ADHD symptoms themselves. The pathway appeared to run specifically through executive function, not through diagnostic outcomes.

This distinction matters. ADHD symptoms are influenced by many factors and often fluctuate across development. Executive function, by contrast, provides a more stable window into underlying cognitive processes. The findings suggest that early environments may shape these processes without necessarily altering whether a child meets diagnostic criteria.

The study challenges the assumption that high early activity is inherently problematic. In many clinical settings, high activity is viewed as an early warning sign. Yet the research suggests a different interpretation. High activity in infancy may reflect openness to input, curiosity, and responsiveness. These traits can support strong development when the environment is structured, predictable, and rich in stimulation. They can also magnify difficulties when support is lacking.

Experts involved in the research argue that biological sensitivity to the environment can be detected far earlier than previously recognised. The neonatal period, often seen as too early for meaningful psychological assessment, may already reveal individual differences with long‑term significance. Sensitivity, in this view, is not a fixed category but a continuum shaped by both the child and the parents.

This perspective carries important implications for early support. If some children are especially responsive, they may benefit most from targeted enrichment. This does not mean labelling infants as destined for difficulty.

Instead, it suggests prioritising resources where they are likely to have the greatest effect. Families in which parents also have ADHD symptoms may face additional challenges in creating structured and stimulating environments. Supporting these families early could yield lasting benefits for children who are most sensitive.

At the same time, the researchers urge caution. The study involved a relatively small sample and included only boys. Results may not generalise to girls, who often show different developmental patterns in ADHD. Temperament was assessed through parent report, which can be influenced by parental perceptions and expectations. ADHD outcomes were exploratory rather than diagnostic. Early sensitivity should therefore be understood as a probabilistic marker, not a prediction.

The findings also raise broader questions about how society understands risk and resilience. Labels such as “at risk” or “resilient” imply fixed traits. The emerging evidence points instead to flexibility. A child’s developmental path is shaped by ongoing interactions between biology and environment. Traits that look like risk in one context may become strengths in another.

Future research will need to expand on these insights. Larger studies, including girls and diverse cultural settings, are essential. Combining behavioural measures with biological markers such as genetics, brain activity, or stress physiology could refine understanding of sensitivity. Most importantly, intervention studies are needed to test whether enhancing early environments can truly alter long‑term outcomes for children identified as highly responsive.

For now, the study offers a fresh lens on ADHD risk. It suggests that the story begins earlier than expected, and that early differences are not simply signs of disorder. They may be signals of potential.

Recognising and supporting that potential, especially in families already facing challenges, could change the developmental trajectory of children who are often misunderstood.

It reflects a growing shift in developmental science, away from deterministic models and towards a more hopeful, context‑sensitive view of child development.