What Role Do Genetics Play in ADHD Combined Type? 

ADHD is often misunderstood as just a behavioural issue, but it is far more complex. At its core, it’s a neurodevelopmental condition with strong biological roots and one of the clearest links is geneticsIf ADHD seems to run in your family, you are not imagining it, science supports you. This article explores the genetic basis of ADHD Combined Type, where inattention meets hyperactivity, and explains why understanding inherited ADHD can be so important for families seeking clarity and support. 

Is ADHD Hereditary? 

Yes, ADHD is hereditary. In fact, it is one of the most heritable mental health conditions studied. Family and twin studies consistently show that the risk of ADHD is largely genetic. If a parent has ADHD, their child has about a 50% chance of developing it too. This covers all subtypes, including Combined Type, which is diagnosed when someone shows both inattentive and hyperactive-impulsive symptoms. Often seen across generations, these traits reflect what researchers call a family history of ADHD. Although individual or age-specific symptoms may differ, the underlying heritability remains strikingly consistent. 

How Do Genes Influence ADHD? 

When we discuss ADHD genetics, we are not referring to a single “ADHD gene”. Instead, ADHD is polygenic, meaning it results from the interaction of multiple genes, contributing to total risk Most of these genes influence how the brain regulates key neurotransmitters, particularly noradrenaline and dopamine. Attention, drive, emotional control, and impulse control all depend on these substances in some vital capacity. Disruptions in these systems can lead to the kinds of behaviours seen in ADHD: forgetfulness, restlessness, or difficulty sticking to tasks. Having these genetic traits doesn’t necessarily mean someone will develop ADHD. Environmental factors also play a role in shaping how genetic risk unfolds. Things like parenting style, early life stress, sleep quality, diet, and even screen time can interact with a person’s genetics to influence how and whether ADHD symptoms emerge. 

What Is the Genetic Risk for ADHD Combined Type? 

People with Combined Type ADHD do not possess unique genes, but rather a broader mix associated with both inattentiveness and hyperactivity. So, someone with Combined Type may have inherited genetic vulnerabilities linked to both ends of the ADHD spectrum. There is still more research to be done, but some studies indicate that individuals with more severe or persistent ADHD symptoms may carry a greater ‘genetic load’, that is, a higher number of small genetic variations associated with the condition. This could help to explain why the genetic ADHD risk seems more apparent in families with multiple affected members. 

What If ADHD Runs in the Family? 

You’re not alone if your child’s ADHD diagnosis makes you start noticing similar traits in yourself. In fact, many adults only consider seeking their own diagnosis after realising how much their experiences reflect those of their child. Realising ADHD runs in the family can be emotional, but it’s also empowering. It helps reframe long-standing struggles not as personal flaws, but as part of a shared experience. Understanding your family history means you can act sooner. Families aware of ADHD’s genetic link are more likely to seek early support, reducing the emotional strain that often comes with an undiagnosed condition. 

Can You Get Tested for ADHD Genes? 

Currently, ADHD cannot be diagnosed via a DNA test. Although studies have found particular genetic changes linked to ADHD, these are not applied clinically. Neither commercial nor clinical genetic testing can currently confirm or rule out ADHD. Behavioural assessments, history-taking, and symptom checklists still form the foundation of diagnosis. Consulting a qualified clinician is the best way to avoid relying on commercial ancestry or genetic testing kits if you are worried about ADHD in your family or yourself. 

Final Thoughts 

ADHD, including the Combined Type, has a strong genetic basis. Knowing that it is often inherited helps to reduce the stigma, promote empathy, and foster early diagnosis and treatment. 
Whether in your family, your child, or yourself, if ADHD symptoms are familiar, you should investigate it further. Early insight can truly make a difference. Take our free ADHD self-assessment or explore more about family support and alternative diagnostic pathways.