There is increasing evidence from medical studies that genetic factors play a role in ADHD. Jacquelyn Gillis and her team, then at the University of Colorado, reported in 1992 that the risk of ADHD in a child whose identical twin has the disorder is between 11 and 18 times greater than that of a non-twin sibling of a child with ADHD. She showed that between 55 and 92 percent of the identical twins of children with ADHD eventually develop the condition.
A large study of twins in Norway, involving 526 identical twins (who inherit exactly the same genes) and 389 fraternal twins (who are no more alike genetically than siblings born years apart) found that ADHD had nearly an 80 percent chance of being inherited. They concluded that up to 80 percent of the differences in attention, hyperactivity and impulsivity between people with ADHD and those without the disorder can be explained by genetic factors.
In addition, scientists are telling us that there are genetic mechanisms that regulate hyperactivity, especially as they relate to dopamine. For example, a significant percentage of people with ADHD have been found to have an abnormality of the dopamine D4 receptor gene, which is associated with abnormal risk-taking behavior and hyperactivity.
What does this mean for your family? Simply that one or both of the parents of your ADHD child are likely to have ADHD. If so, dealing with your child may remind you of some painful memories from your childhood or teenage years. This can make it even more difficult and emotional to deal with your child.
Furthermore, the unaffected siblings may be more likely to have children of their own with ADHD. These are just a few of the reasons that many ADHD therapists will recommend that parents and siblings also be tested for ADHD and consider education and counseling for the entire family.
Medical information within this site is not intended for use in the diagnosis or treatment of any health condition. Please consult a licensed health care professional for the treatment or diagnosis of any medical condition.