Is ADHD Genetic? Understanding What Causes ADHD and Why It Matters

Everyone experiences distraction or forgetfulness sometimes, but for people living with Attention Deficit Hyperactivity Disorder (ADHD), these moments can shape daily life. Many spend years wondering why staying focused or organised feels harder for them, often blaming themselves for not trying hard enough. Understanding what causes ADHD and exploring whether ADHD is genetic can offer clarity and compassion. Knowing that ADHD has biological and environmental foundations helps remove guilt and makes room for self understanding and effective care.

This article explores the science behind ADHD, covering genetics, environmental influences, and brain chemistry, and debunks myths so you can approach this topic with knowledge and confidence.

Genetic Factors: The Family Connection

ADHD frequently runs in families, showing a strong genetic foundation. Research from large twin studies estimates ADHD’s heritability at approximately 74%, meaning genetic factors explain nearly 3 quarters of differences in ADHD traits among individuals [1].

Here’s how that looks in real life:

• Identical twins share about an 80% chance of both developing ADHD if one twin has it [2].

• Fraternal twins share around a 30% chance [1].

• A child with a parent who has ADHD faces approximately a 50% chance of developing ADHD themselves [3].

Genes that affect dopamine, such as DRD4 and DAT1, play an important role [4]. Dopamine influences attention, motivation, and reward response. Variations in these genes can subtly alter dopamine activity, increasing ADHD risk. No single gene causes ADHD, but several genes combine to raise susceptibility, which is why ADHD often appears in multiple family members.

Understanding the hereditary side of ADHD helps families recognise that this condition is not a reflection of effort or parenting, it is largely biological and highly influenced by inherited factors.

Environmental Influences: Early Life Experiences and ADHD Risk

Genetics set the stage for ADHD, but environment can add to the picture. Environmental factors, particularly before and shortly after birth, can influence how ADHD develops or how severe it becomes.

Prenatal and Birth Related Factors

Environmental factors increasing ADHD risk include:

• Maternal smoking during pregnancy, clearly linked to higher ADHD risk due to its impact on foetal brain development [5].

• Maternal alcohol use during pregnancy, especially heavy drinking, associated with attentional difficulties in offspring [6].

• Premature birth and low birth weight significantly elevate ADHD incidence, with extremely preterm infants facing approximately 3 to 4 times greater risk compared to full term infants [7].

• Birth complications such as oxygen deprivation, which stress developing brains, increasing later ADHD risks [8].

Early Childhood Factors

Other influential early life experiences include:

• Lead exposure, even at low chronic levels, has been linked to increased ADHD behaviours [9].

• Severe early adversity such as neglect or institutionalisation is associated with increased ADHD symptoms through impacts on brain stress response systems [10].

• Excessive screen time and poor sleep habits can exacerbate symptoms, although these factors alone do not directly cause ADHD [11].

Environmental influences tend to amplify genetic risk rather than act independently. A child who inherits ADHD vulnerability might see stronger symptoms if exposed to these early risks.

For further reading, see our article on ADHD treatment and management options.

ADHD and Your Brain: The Neuroscience Behind Symptoms

ADHD is not due to laziness or lack of effort. It is a neurodevelopmental condition with measurable brain differences.

Dopamine’s Crucial Role

Individuals with ADHD typically show reduced dopamine activity, especially in areas controlling attention and motivation [12]. Stimulant medications effectively increase dopamine levels, significantly improving

ADHD symptoms in about 70% to 80% of individuals [13, 18].

You might recognise dopamine’s role in daily challenges:

• Losing focus on tasks without immediate rewards

• Constantly seeking excitement or stimulation

• Finding motivation only when deadlines or urgency are involved

These experiences reflect how ADHD affects reward sensitivity, not a lack of willpower.

Structural Brain Differences

MRI studies demonstrate structural differences in ADHD brains, particularly in regions such as the prefrontal cortex, which matures approximately 2 to 3 years later and is about 3% to 5% smaller in volume compared to those without ADHD [14, 17].

These measurable differences validate ADHD as a brain based condition. Understanding them can help replace guilt or frustration with insight and practical steps forward.

Myths About ADHD: Setting the Record Straight

Misunderstandings about ADHD have persisted for decades, often creating unnecessary stigma. Here are some truths grounded in evidence:

• Myth: ADHD is caused by bad parenting. Fact: Parenting style does not cause ADHD. While positive routines help manage symptoms, the condition itself is biological [15].

• Myth: ADHD results from too much sugar. Fact: Controlled studies consistently show no evidence linking sugar intake to ADHD development [16].

• Myth: ADHD comes from excessive screen time. Fact: While screen use can aggravate existing attention issues, it does not cause ADHD [11].

• Myth: ADHD is not real. Fact: ADHD is recognised internationally by medical authorities and supported by neurobiological evidence [3].

Clearing up these misconceptions helps shift focus from blame toward support and understanding.

ADHD as a Multifactorial Condition

ADHD develops through the interplay of genetics, environment, and neurobiology. Most often, these elements overlap rather than act independently.

• Genetics create susceptibility.

• Prenatal factors and early exposures further shape development.

• Structural and chemical brain differences manifest in behavioural symptoms.

Understanding this multifaceted nature promotes compassionate self understanding rather than blame.

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Frequently Asked Questions about ADHD Causes

Is ADHD purely genetic?

ADHD has strong genetic foundations, around 74% heritability, but environmental factors also significantly influence whether ADHD fully develops [1].

Exactly how heritable is ADHD?

It is approximately 70% to 80%, making it one of the most heritable mental health conditions [2].

Can someone develop ADHD solely from environment?

Rarely. Genetic vulnerabilities almost always play a part, but environment can intensify or trigger symptoms [8].

Are there specific genes responsible for ADHD?

ADHD is polygenic, meaning many genes contribute small effects together rather than one acting alone [4].

How does understanding ADHD’s causes help?

Recognising ADHD's genetic and neurological roots guides treatment strategies, combining medication for neurochemical balance and behavioural strategies for environmental support [13, 18].

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At Nurtured Thoughts Psychology, we understand how confusing and frustrating living with ADHD can feel. Our team offers comprehensive ADHD assessments and evidence based treatment tailored to your unique profile.

Here are some simple strategies that may help manage symptoms, discussed best with a professional:

• Build structure through consistent daily routines.

• Use short, focused time blocks such as 15 minute sessions for complex tasks.

• Explore ADHD focused therapies like cognitive behavioural therapy or ADHD coaching.

• Discuss medication options that suit your needs and lifestyle.

If symptoms begin to feel unmanageable or overwhelming, reach out to a mental health professional for support. Our clinicians can help you find balance and confidence through understanding, practical tools, and compassion.

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References

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[2] Demontis, D., Walters, R. K., Martin, J., et al. (2019). Discovery of the first genome wide significant risk loci for ADHD. Nature Genetics, 51(1), 63–75. https://doi.org/10.1038/s41588-018-0269-7 

[3] Thapar, A., & Cooper, M. (2016). Attention deficit hyperactivity disorder. The Lancet, 387(10024), 1240–1250. https://doi.org/10.1016/S0140-6736(15)00238-X 

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[8] Thapar, A., Cooper, M., Eyre, O., & Langley, K. (2013). What have we learnt about the causes of ADHD. Journal of Child Psychology and Psychiatry, 54(1), 3–16. https://doi.org/10.1111/j.1469-7610.2012.02611.x 

[9] Nigg, J. T., Knottnerus, G. M., Martel, M. M., et al. (2008). Low blood lead levels associated with clinically diagnosed ADHD and mediated by weak cognitive control. Biological Psychiatry, 63(3), 325–331. https://doi.org/10.1016/j.biopsych.2007.08.010 

[10] Roy, P., Rutter, M., & Pickles, A. (2004). Extremely deprived children in UK foster care, developmental catch up and adaptation. Child Development, 75(2), 472–490. https://doi.org/10.1111/j.1467-8624.2004.00688.x 

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[13] Faraone, S. V., Bellgrove, M., Brikell, I., et al. (2024). Attention deficit hyperactivity disorder. Nature Reviews Disease Primers, 10(1), 29. https://doi.org/10.1038/s41572-024-00518-w 

[14] Hoogman, M., Bralten, J., Hibar, D. P., et al. (2017). Subcortical brain volume differences in participants with ADHD in children and adults, a cross sectional mega analysis. The Lancet Psychiatry, 4(4), 310–319. https://doi.org/10.1016/S2215-0366(17)30049-4 

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[18] Efron, D., & Coscini, N. (2025). Pharmacological management of attention deficit hyperactivity disorder in children and adolescents. Australian Prescriber, 48, 156–160. https://doi.org/10.18773/austprescr.2025.043