This is part one of a two-part series on the links between heredity and autism, attention deficit hyperactivity disorder (ADHD), and anxiety disorders.

Guilt, worry, self-blame. Parents of children diagnosed with autism spectrum disorder, anxiety disorder, or attention deficit hyperactivity disorder (ADHD) are often plagued with such feelings.

As parents, you search for answers and seek second opinions. But through it all, you may question your own medical history and genetic background. Could these neurobehavioral disorders be biological? Or learned behavioral traits that get passed on?

Researchers haven't determined what causes these disorders, but family history is a key suspect.

Matthew Larsen, DO, a resident psychiatrist at Eastern Idaho Regional Medical Center, provides insight into the causes of these neurobehavioral conditions in our two-part series on mental health disorders.

Genetic Link

“ADHD is the most likely of the three disorders to be hereditary,” Dr. Larsen explains. “But the likelihood of a child's parents passing on an ADHD gene is still small.”

“Anxiety has a very, very small genetic link,” he adds. “As for the causes of autism, researchers are very uncertain as to what the link is.”

Dr. Larsen further explains that there seems to be some type of genetic relationship for autism, since parents who are autistic are more likely to have a child who is autistic.

But researchers haven't yet found a great correlation between the two to give a definitive answer as to a genetic link.

Children who have a sibling with autism are at a higher risk of also having autism, according to the Centers for Disease Control and Prevention (CDC).

And certain genetic or chromosomal conditions, such as fragile X syndrome or tuberous sclerosis, have also been associated with developing autism.

Adopted Behaviors Vs. Inherited Behaviors

“Yes, it is possible for these disorders to be, in part, a learned behavior,” Dr. Larsen says. “But it's usually a combination of learned and inherited behaviors.”

Anxiety seems to be the disorder that is most based on environmental factors, as it is usually a learned disorder based on real life experiences as opposed to just genetics.

Some parents may use perfectionism and overcontrol to manage their own anxiety, which together have been shown to increase the risk for anxiety in children, according to an April 2015 study published in the Journal of Abnormal Child Psychology.

Children may see their parent in stressful situations and learn from the parent's response.

“You can have the best child psychologist in the world, and their own child may end up with anxiety,” Dr. Larsen says. “Because knowing what to do and actually doing it when facing stressful situations in life are two different things.”

As for ADHD and the causes of autism, there is not enough evidence associating the disorders to either inherited or learned behaviors, says the CDC.

Possible Contributing Risk Factors

Researches are scrambling to study the risk factors and causes of autism, ADHD, and anxiety in an effort to find better ways to manage and reduce the occurrence of these disorders.

For the time being, we know that genetics plays an important role. But there are also possible risk factors that contribute to each disorder, including environmental, biological, and genetic factors.

Sources: Centers for Disease Control and Prevention (1, 2), American Journal of Psychiatry

Is Genetic Testing Recommended?

In an effort to better diagnose and treat these mental health disorders, many parents are interested in genetic testing of their children. However, Dr. Larsen warns that genetic testing can come with a hefty price tag, and the findings may not always be helpful.

“There's anecdotal evidence of genetic tests, but none have been proven on a large scale,” he says.

“There are many, many companies offering genetic testing for a wide array of problems,” Dr. Larsen says. “But they are kind of like a full-body CT scan. They may identify something that is not typical, but that doesn't mean it's a problem.”

“All physical differences don't cause problems, just like all genetic differences don't cause problems,” he adds. “The tests that are currently available are currently only useful for furthering research.”

For the time being, parents will have to contend with the various treatment options available for autism, ADHD, and anxiety.

In part two, Dr. Larsen discusses the latest on treatment options and coping strategies that best suit each disorder.

Looking for expert advice regarding your child's mental health? Schedule an appointment with an Eastern Idaho Regional Medical Center psychiatrist.