The short version
ADHD is a recognised neurodevelopmental condition described by persistent patterns of inattention and/or hyperactivity and impulsivity with functional impact. The outward pattern can differ across people, settings and life stages. A diagnosis requires a structured assessment; a single behaviour, questionnaire score or gene result does not establish it.
The usual mix-up
“A quiet or high-performing person cannot have ADHD.” A visible result cannot, on its own, explain the process behind it.
Next
Look for the sustained cost of functioning across settings, including compensatory effort.
What genes can and cannot tell you
- ADHD runs in families. Twin studies put heritability at about 74% (Tier B). That describes differences across a population, not a share of any one person's ADHD.
- There is no single “ADHD gene”. The picture is thousands of common variants that each nudge risk a tiny amount, plus rarer variants with bigger effects, plus chance and environment (Tier B).
- Genes describe risk. They are not a diagnostic test and they do not tell a clinician which medication to use (Tier B).
- Some rare single-gene conditions affect the same dopamine pathways and can produce movement symptoms. That is a differential diagnosis question for specialists, not proof that ADHD is caused by those genes (Tier A for the conditions, Tier D for any link to ADHD).
Read the genetics series: ten plain-English articles, each with its evidence tier, limits and sources.
Limits
This page is general information. Personal experience varies. A source supporting a clinical framework does not automatically validate every suggested coping technique or prove an individual causal mechanism. Claims are dated, jurisdiction-limited where relevant, and should be corrected when stronger evidence changes the conclusion.