Child’s DNA Drives ADHD Traits, Study Finds

Researchers from King’s College London and Norwegian partners examined data from the Norwegian Mother, Father and Child Cohort Study, which includes 12,374 family trios when children were five and 12,714 trios when they were eight. They used trio genome‑wide complex trait analysis to look at the combined influence of about one million single‑nucleotide polymorphisms in mothers, fathers and children, and compared parents’ indirect genetic effects with the child’s direct genetic effects on overall ADHD scores.

child’s direct genetic effect

At age five the initial models suggested a small indirect effect from mothers, but more stringent statistical tests found no reliable evidence of either direct or indirect genetic influence. By age eight the data showed that the child’s own genetics explained roughly eight percent of the variation in ADHD traits, while indirect effects from either parent were again not supported.

The results imply that by mid‑childhood a child’s DNA is the main biological driver of ADHD symptoms, although the study’s large error margins mean subtle parental genetic influences could still exist. Limitations include reliance on mothers’ ratings, a sample limited to families of European ancestry, and the use of total ADHD scores rather than specific symptom domains, suggesting that larger, more diverse studies are needed to confirm these patterns.