Much research has been done on how you get ADHD, and it is now known that genetics is at least part of the reason. Current research demonstrates that at least 30%-40% of individuals with ADHD have a family member that is experiencing the same kinds of issues. However, this does not mean that the entire family will be affected by these issues; findings indicate that when more family members are affected, it is usually limited to one member.

There are many different theories as to what exactly causes ADHD. For many years, it was thought that ADHD was caused by some kind of brain damage; however, it is now believed to be caused by brain chemistry. Researchers have been looking specifically at neurotransmitters as the cause of ADHD. Examples of neurotransmitters that could be affected by this disorder are dopamine, norepinephrine and serotonin. Because people in families tend to have similar brain wirings, it makes sense that ADHD would be at least partly genetic.

Other theories that have been investigated are that ADHD could also be caused by some sort of illness or accident that produced damage to the brain. Possible examples include complications that had occurred during pregnancy, such as drugs used to prevent infectious diseases, consuming alcohol, overexposure to radiation or a complicated delivery.

Many have questioned whether nutritional deficiencies are linked to ADHD. Although this has not been ruled out, it is doubtful that a particular deficiency would cause this disorder. While it is true that certain nutritional deficiencies will cause symptoms that are similar to ADHD, there is no proof or scientific evidence that a link exists. Research experts in autism and other behavior disorders have looked for a nutritional link as well, but have found none. However, there has been some evidence that the Feingold diet may help diminish symptoms of ADHD.

Since the diagnosis of ADHD has become so much more common in recent years, it is often that an older family member will get diagnosed while bringing their son or daughter in to get tested. This may provide some relief to individuals who weren't sure exactly why they were the way they were, and explain some part of the individual's life that did not make sense before. Some of those diagnosed late may decide to go on medication upon diagnosis, while others may not.

If there are no other members of a family that have ADHD per se, there may be other similar disorders. Although there is no formal link between autism and ADHD, there are similarities, and the two disorders tend to run together. Family background may include someone with autism, Asperger's Syndrome, bipolar or OCD; these are mainly brain based disorders that have been loosely linked to ADHD and are sometimes co-morbid.