Some, but not all, mental illnesses are hereditary and can be passed down to children by either parent. If both parents have the same mental illness, the child is more likely to get it. Sometimes children will display signs of a mental illness early on, but many mental illnesses do not begin to show symptoms until they are in their late teens or early adult years.
How DNA Plays a Role in Mental Illness
DNA was first identified in 1896, but the question of who discovered DNA and who studied it most is debatable, with Watson, Crick, and Miescher being some of the most formidable early DNA scientists. Once DNA, and the genes they work to make up, were discovered, scientists were able to study them more carefully to determine how traits were passed down from parent to offspring. Before the discovery of DNA, scientists knew that some traits were passed down, but they were not confident about how they were passed down.
There are two general ways that genes can play a role in mental illnesses. The first way is by passing a “mental illness” gene from parent to child. Having one of these genes doesn’t necessarily mean a person will show symptoms of a mental illness later in life, just that they are more likely to than a person without the gene. The second way is through random genetic mutations, which cannot be predicted or prepared for.
Hereditary Mental Illnesses
As mentioned, having a “mental illness” gene doesn’t necessarily mean a person will become mentally ill. There is no one gene that causes mental illness, but a variety of genes that are more likely than others to cause mental illness. Below are the top ten mental illnesses that are most likely to be passed down through genetics, in order of likelihood of the illness being passed down.
- Schizophrenia
- Generalized Anxiety Disorder
- Depression
- Bipolar Disorder
- Obsessive-Compulsive Disorder
- Attention Deficit Hyperactivity Disorder
- Eating Disorders (Various)
- Postpartum Depression (Mothers only)
- Addiction (Various)
- Phobias (Various)
If one parent has one of these disorders, a child may eventually have it too. If both parents have the same disorder, then the child has a higher chance of having it later in life. A person can have more than one mental illness. Some mental illnesses share symptoms, which can make them difficult to diagnose.
Environment and Mental Illness
While genes play a part in mental illness, they don’t have the final say. A person’s environment, how they are raised, and exposure to trauma play a bigger part in whether a person will display symptoms of mental illness. According to genetic researcher Behm, only about 5% of diseases are determined by genes. That means that the rest are determined by the environment.
The better home environment a child has growing up, the less likely they will be to display symptoms of a mental illness later in life. There is no one way to have a good home life. So long as a child is happy and healthy, they will be more likely to not develop a mental illness. If the child’s life is full of trauma, stress, abuse, or family fighting and instability, then they will be more likely to show symptoms of mental illness later. These negative factors “trigger” mental illness symptoms. If left unrigged, the symptoms are less likely to develop into a full-blown mental illness.
Even people who do not have a family history of mental illness can still show symptoms. This is also often caused by the environment they were up in, or major stress or trauma that occurs as an adult, like PTSD or abuse. The same things that might trigger mental illness symptoms in a child with a genetic predisposition can also trigger mental illness in a child without a genetic predisposition.
While mental illnesses are not totally preventable, providing a healthy growing environment for a child will make it less likely that they will experience mental illness as an adult. Genes and DNA do play a part, but they are not the be-all, end-all when it comes to mental illness.
