Skip to main content
ADHD Private
Symptoms · 18 min read

Is ADHD genetic or hereditary? What family history means

ADHD often runs in families. What twin studies show, what heritability means, why no genetic test can diagnose it at present, and what UK services say.

Written and maintained by the ADHD Private editorial team, drawing on the sources listed at the end of this article. This is general information, not medical advice.

At a glance

Yes, in the sense that ADHD often runs in families. The NHS website for England says ADHD “may be caused by genetic differences and often runs in families”, and the Royal College of Psychiatrists says that for most people it is caused by a combination of genetic and environmental factors. Having a parent or sibling with ADHD makes it more likely, not certain, and no genetic test can diagnose it at present.

It is general information, not medical advice. We opened every source below on 9 October 2026 (“abstract read” marks studies where we read only the abstract), and give the heritability and family-risk figures with the design, population and country their source states.

Is ADHD genetic?

The public health pages of the four UK nations do not all use the same words (on this topic NHS 111 Wales repeats the NHS website’s sentences). NICE and the Royal College of Psychiatrists are added for comparison:

Service (nation)What it says about family and genesDate the page shows
NHS website (England), pages for adults and for children and young people“The cause of ADHD is not always known. ADHD may be caused by genetic differences and often runs in families.”Reviewed 19 March 2025
NHS 111 Wales, pages for adults and for children and young peopleThe same two sentences, on pages NHS Wales says it adapted from the NHS websiteLast updated 4 July 2025
NHS inform (Scotland), pages for adults and for children and young people“The cause of ADHD is not known. A combination of factors might be responsible.” Its list of things linked to ADHD begins “having a sibling or parent with ADHD”.Last updated 23 June 2026 (adults) and 18 June 2026 (children and young people)
nidirect (Northern Ireland), a page about children“The exact cause of ADHD is unknown, but the condition has been shown to run in families.”No date shown
NICE guideline NG87 (England and Wales)Lists “people with a close family member diagnosed with ADHD” among groups that “may have increased prevalence of ADHD compared with the general population”Published 14 March 2018, last updated 13 September 2019
Royal College of Psychiatrists (the quoted sentences state no nation)Parents’ page: “For most people, ADHD is caused by a combination of genetic and environmental factors.” Adults’ page: “People who have a direct relative who has ADHD are also more likely to have ADHD themselves.”Published April 2025 (parents) and June 2023 (adults)

A 2019 review by Faraone and Larsson says that family, twin and adoption studies “show that ADHD runs in families”, and that adoption studies “suggest that the familial factors of ADHD are attributable to genetic factors rather than shared environmental factors”.

There is generally no single “ADHD gene”. The Royal College of Psychiatrists says the genetic factors are “generally made up of lots of small genetic differences rather one single gene” (the page’s own wording). A 2023 genome-wide study of 38,691 people with ADHD and 186,843 controls, from Denmark, Iceland and ten other European-ancestry cohorts, found 27 regions of the genome linked to ADHD and called it “highly polygenic, influenced by thousands of variants”. Faraone and Larsson write that “no common DNA variants are necessary and sufficient causes of ADHD”.

Rare variants with larger effects exist. Faraone and Larsson write that “in rare cases, a single genetic defect may lead to ADHD in the absence of other DNA variants”, and a 2026 Nature exome-sequencing study of rare coding variants in 8,895 people with ADHD and 53,780 controls implicated three genes.

What does “heritable” mean?

Twin studies rely on “the difference between the within-pair similarities” of identical twins, who are genetically identical, and non-identical twins. The result is a heritability figure, and it describes a population. Thapar and colleagues write that “familial and genetic risks only increase the probability of ADHD and do not determine the presence of disorder”. A heritability figure is therefore not a prediction for one person or family, and this guide gives no “chance” for any family.

FigureWhat it measuresDesign, population and year
74%Mean heritability across 37 twin studies of ADHD or of measures of inattention and hyperactivityTwin studies from several countries, covered in a review by Faraone and Larsson (2019). The 2021 consensus statement lists the United States, Europe, Scandinavia and Australia.
77 to 88%The few of those studies that used categorical measures of ADHD rather than symptom countsThe same review
88% (95% confidence interval 83 to 92)Heritability of ADHD recorded in Swedish national registers (a diagnosis or ADHD medication)59,514 twins born in Sweden between 1959 and 2001 (Larsson and colleagues, 2014)
72% (95% confidence interval 56 to 84)The same measure, adults onlyThe same study
14%Variation in liability to ADHD in the study accounted for by common DNA variants measured across the genome (“SNP heritability”)A genome-wide study of 38,691 people with ADHD and 186,843 controls from Denmark, Iceland and European-ancestry cohorts (Demontis and colleagues, 2023).
What none of these is“Heritability estimates refer to populations and do not mean for example that 90% of an individual’s ADHD is caused by genes.” (Thapar and colleagues, 2013)

The figures differ partly because of what was measured. Faraone and Larsson (2019) say the first twin studies of ADHD in adults used self-reports and estimated heritability at 30 to 40%. Larsson and colleagues’ 72% for diagnosed ADHD in adults led them to conclude that the low reports are likely explained by rater effects.

How much more often does ADHD appear in relatives?

The figures below from Swedish studies of relatives are ratios, not chances. A Swedish cohort study (Chen and colleagues, 2017) identified relatives among 1,656,943 people born in Sweden between 1985 and 2006 and followed them from their third birthday to 31 December 2009 for an ADHD diagnosis. Each figure below is a hazard ratio adjusted for birth year: “the rate of ADHD in relatives of ADHD-affected index persons compared with the rate of ADHD in relatives of unaffected index persons”.

Relative of a person with ADHDHazard ratio, compared with relatives of people without ADHD
Identical (monozygotic) twin70.45
Non-identical (dizygotic) twin8.44
Full sibling8.27
Maternal half-sibling2.86
Paternal half-sibling2.31
Full cousin2.24
Half cousin1.47

Source: Swedish population-based cohort, ADHD diagnosis, people born 1985 to 2006, published 2017.

The ratios fall as the relationship becomes more distant. The authors conclude that “familial aggregation of ADHD increases with increasing genetic relatedness”, and that it is “driven by not only genetic factors but also a small amount of shared environmental factors”.

This guide gives no single percentage for the chance that a child of a parent with ADHD will have ADHD. A 2021 systematic review found four studies of children of parents with ADHD that met its inclusion criteria. All four found more ADHD in those children than in comparison children, but the results differed widely, and the authors say the high heterogeneity suggests the studies were “not estimating a common prevalence”. We searched the pages listed under Sources from the NHS, NHS 111 Wales, NHS inform, nidirect, NICE and the Royal College of Psychiatrists on 9 October 2026 for “chance”, “likelihood” and “probab” and read their passages on family and genes; none gives a percentage for passing ADHD on.

Can ADHD come from your mother or your father?

A 2026 Swedish register study (Yao and colleagues, Molecular Psychiatry) followed children born in Sweden between 2000 and 2014 from birth until emigration, death or 31 December 2020. A parent counted as having ADHD if the registers held an ADHD diagnosis or ADHD medication record. The table gives the adjusted hazard ratio for ADHD in the child, compared with children whose parents both had no ADHD record, adjusted for the parents’ education and psychiatric conditions.

Which parent had ADHDAdjusted hazard ratio for ADHD in the child (95% confidence interval)
Mother only4.96 (4.81 to 5.12)
Father only4.27 (4.13 to 4.42)
Both parents7.05 (6.47 to 7.67)

Source: Swedish national registers, children born 2000 to 2014, followed until 31 December 2020 at most, published 2026. These are ratios of rates, not chances.

The abstract says: “Rates were elevated for both maternal and paternal ADHD”. Across the outcomes studied (ADHD was one of 24), the authors call the pattern “generally similar for maternal and paternal ADHD, while the highest risks were observed when both parents had ADHD”. For ADHD in the child, the ratio was somewhat higher with maternal ADHD than paternal (4.96 and 4.27), and the Results put the highest rates for psychiatric disorders with both parents, “followed by maternal-only ADHD”.

The authors say the study’s design “does not allow causal disentangling of genetic liability, offspring-related pathways, and environmental influences”. Parents’ and children’s diagnoses were based on specialist-care and prescribed-medication records: “individuals managed solely in primary care or those who did not seek treatment were not captured”.

None of the NHS, NHS 111 Wales, NHS inform, nidirect, NICE or Royal College of Psychiatrists ADHD pages we read says that ADHD passes through one parent. We searched the ADHD text of each page on 9 October 2026 for “mother”, “father”, “maternal” and “paternal” and found no match.

Wondering what the next step looks like?

Only a qualified clinician can diagnose ADHD. Answer a few questions and we’ll shortlist clinics that assess people like you.

Find your match

What else is linked to ADHD?

UK health services name several other things linked to ADHD, but “linked” is not “caused by”. The Royal College of Psychiatrists’ parents’ page says of the factors on its list: “This does not necessarily mean that these things cause ADHD.” The 2021 consensus statement calls features of the pre- and post-natal environments that increase risk for ADHD “correlates, rather than causes”. The first four rows below are named as factors in the causes sections of at least one of the services we read; the last three are not.

FactorNamed by (in the pages we read)What the sources we read say
A close family member with ADHDAll the services in the first tableHigher rates in relatives in the Swedish studies above
Being born early (the NHS says before 37 weeks of pregnancy), or a low birth weightNHS, NHS 111 Wales, NHS inform, nidirect (also low birthweight), NICE, Royal College of PsychiatristsAn association found across studies: odds ratio 3.04 (95% confidence interval 2.19 to 4.21) for very or extremely preterm, or very or extremely low birth weight, in a meta-analysis of 12 studies of 1,787 people (Franz and colleagues, 2018)
Epilepsy, a brain injury, being autisticNHS, NHS 111 Wales, NHS inform, NICE, Royal College of PsychiatristsNamed as linked. This guide gives one figure about families of autistic people (see “Common questions”).
Smoking in pregnancynidirect, with alcohol and drug abuse in pregnancy: “suggested as potentially having a role”The link falls away in sibling comparisons (Skoglund and colleagues, 2014)
SugarNot in the cause lists we readThe 2021 consensus statement reports a meta-analysis of seven studies that “found no evidence of an association between sugar consumption and ADHD in youth”. The same statement reports a small association between added-sugar intake and inattention symptoms in about 18,000 Swedish twins, and the Royal College of Psychiatrists says studies link certain foods to some symptoms. Neither says sugar causes ADHD.
ParentingNot in the cause lists we read“No one is ‘to blame’ for ADHD” (Royal College of Psychiatrists)
ScreensNot in the cause lists we readIn 2,587 adolescents from ten Los Angeles County, California, high schools (a convenience sample) with no significant ADHD symptoms at the start, followed for up to 24 months (Ra and colleagues, 2018), frequent digital media use was associated with later self-rated ADHD symptoms (a “modest association”). “Further research is needed to determine whether this association is causal.”

On being born early, sources differ in how they describe cause. A Swedish register study of 1,180,616 children born between 1987 and 2000 (Lindström and colleagues, 2011), which used ADHD medication in 2006, at age 6 to 19, as its measure of ADHD, found odds rising stepwise with earlier birth. Its authors conclude the main effect “is not explained by genetic, perinatal, or socioeconomic confounding”. A 2013 review (Thapar and colleagues) listed prematurity as a risk factor whose causal role had not been shown.

Of the pregnancy exposures nidirect lists, this guide reports research on smoking only. In a Swedish register study of 813,030 people born between 1992 and 2000 (Skoglund and colleagues, 2014), the link between smoking in pregnancy and ADHD in the child shrank as the comparison moved closer to the family. Between siblings the hazard ratios were 0.88 and 0.84, for moderate and high smoking. The paper’s 95% confidence intervals (0.73 to 1.06 and 0.65 to 1.06) include 1, so this is not evidence that smoking in pregnancy protects against ADHD.

The authors say their results “suggest” the association is “due to unmeasured familial confounding”, and the 2021 consensus statement says it “disappears after adjusting for family history of ADHD”. Thapar and colleagues add that there are “clear health benefits of mothers not smoking” in pregnancy, so this finding concerns ADHD only.

On parenting, NICE tells clinicians to explain to parents that any recommendation of parent training “does not imply bad parenting”. On wider adversity, a 2013 review (Thapar and colleagues) said that, apart from rare exposure to extreme early adversity, there was “no clear-cut evidence that psychosocial adversity causes ADHD, although such factors may well modify its expression and outcomes”.

Is there a genetic test for ADHD?

No genetic test can diagnose ADHD at present. Thapar and colleagues concluded in 2013 that the genetic risks identified for ADHD “cannot be used for prediction, genetic testing or diagnostic purposes beyond what is predicted by a family history”, and the 2021 consensus statement says findings on rare causes of ADHD-like symptoms, including “a single genetic abnormality”, “are not useful for diagnosing the disorder”. NICE’s recommendations page does not mention genetic testing: we searched it for “genetic” and “DNA” on 9 October 2026 and found no match.

NICE (England and Wales) says ADHD “should only be diagnosed by a specialist psychiatrist, paediatrician or other appropriately qualified healthcare professional”, on the basis of “a full clinical and psychosocial assessment of the person”, a full developmental and psychiatric history and observer reports. It also says a diagnosis “should not be made solely on the basis of rating scale or observational data”.

The Royal College of Psychiatrists’ page for parents says “There is no one test for ADHD”, and NHS inform says “There isn’t a single test or checklist that can confirm if a child has ADHD or not.” If a genetic test is offered to you in connection with ADHD, none of the sources above says it can diagnose ADHD or tell you whether a child will have it.

If a child has ADHD, could a parent have it too?

A family history is a reason for awareness, not a diagnosis. NICE asks clinicians to be aware that people with “a close family member diagnosed with ADHD” may have increased prevalence of ADHD compared with the general population, and to “Think about the needs of a parent with ADHD who also has a child with ADHD”. An assessment, on the basis NICE sets out above, decides whether an adult has ADHD.

If you are a woman and recognise yourself in your child’s traits, our guide to ADHD in women covers what the sources say about how it can look and why it can be missed. Where to start, by nation:

  • England. The NHS website says: “If your ADHD symptoms are affecting your studies, work or relationships, make an appointment with a GP to find out what support is available.”
  • Wales. NHS 111 Wales gives the same advice on its adult page.
  • Scotland. NHS inform says: “Speak to your GP practice if you think that you may have ADHD and it’s having a negative effect on your life.” It also says: “Your local NHS health board or GP practice may not accept the outcome of a private assessment.”
  • Northern Ireland. nidirect’s ADHD page is written about children and says to “tell your doctor your concerns”. In a freedom of information reply dated 30 June 2026 about waiting times, assessments and the assessment pathway, the Department of Health said “There is currently no commissioned service for ADHD in Northern Ireland” and suggested contacting the HSC Trusts.

Common questions

Is ADHD genetic or environmental?

For most people, both. The Royal College of Psychiatrists says that for most people with ADHD “the condition is caused by a combination of genetic and environmental factors”, and the NHS says “The cause of ADHD is not always known.”

What percentage of ADHD is genetic?

There is no single answer. The estimates in that table depend partly on the design and on how ADHD was measured, and each describes a studied population, not one person. See the table under “What does ‘heritable’ mean?”.

Are ADHD and autism inherited together?

They are linked in families. In a Swedish register-based study of 1,899,654 people born between 1987 and 2006 (Ghirardi and colleagues, 2018), full siblings of people with autism had higher odds of clinically ascertained ADHD than relatives of people without autism (odds ratio 4.59, 95% confidence interval 4.39 to 4.80). The authors say the pattern “supports the existence of genetic overlap between clinically ascertained ASD and ADHD”. The 2023 genome-wide study said its model of shared variants for ADHD and autism had “limited support” and should be read with caution. Our guide to AuDHD covers ADHD and autism together.

Can ADHD skip a generation or come from a grandparent?

We did not find a study of ADHD skipping a generation, and our title search found none on ADHD passing from a grandparent to a grandchild. We searched PubMed on 9 October 2026 for titles that name ADHD (as “ADHD” or in full) together with grandparent, grandchild, grandmother or grandfather (including word endings), “third generation”, “three-generation” or “skipped generation”. The three results concerned a caregiving arrangement, smoking in pregnancy and grandmothers’ weight.

Can ADHD start in adulthood?

The NHS says ADHD symptoms “usually start before the age of 12”. NICE (England and Wales) says adults with symptoms who do not have a childhood diagnosis should be referred for assessment where, among other criteria, there is evidence of typical features that “began during childhood and have persisted throughout life”. Not having been diagnosed as a child is a separate matter: NICE’s recommendation covers adults “who do not have a childhood diagnosis of ADHD”.

Finding a clinic

A family history is not a diagnosis. If you are thinking about an assessment for yourself, you can compare private clinics that list assessments for adults on our adult clinics page. For a child, see our children’s clinics page.

In England, Right to Choose is one NHS route. The NHS says you can ask for an NHS appointment at a clinic, including a private clinic, if it provides ADHD services for the NHS in England. It starts with a referral: NHS England’s patient choice guidance says, “The legal rights do not extend to self-referrals or any referral other than from or on behalf of a GP, Dentist, or Optometrist.”

Our Right to Choose guide explains the steps.

Sources

Sources checked on 9 October 2026.

Share

Cite this page: ADHD Private (2026). “Is ADHD genetic or hereditary? What family history means”. adhdprivate.co.uk, published 9 October 2026. https://adhdprivate.co.uk/symptoms/is-adhd-hereditary