Can Phobias Be Inherited? Fear, Genes and Epigenetics
Author: Thomas C. Weiss
Published: 11 Aug 2014 - Updated: 8 Nov 2026
Publication Type: Informative
Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content
Synopsis
This information looks at the evidence that fear, phobias and the effects of trauma can be passed from one generation to the next. Written by Thomas C. Weiss, it describes the Emory University study by Brian Dias and Kerry Ressler, published in Nature Neuroscience in 2013, in which mice trained to fear a cherry blossom-like scent had offspring and grandoffspring that startled at the same smell, apparently through chemical marks on sperm DNA. It also covers a Virginia Commonwealth University twin study led by Dr. John Hettema, which found that between one-third and one-half of fear conditioning appears to be inherited. The material is useful for people living with anxiety disorders, phobias or PTSD and their families, because it helps explain why fears sometimes run in families and points to new ways of understanding and treating these conditions.*
At a Glance
- 1 - Fear has long been thought of as a purely learned response.
- 2 - The offspring of the trained mice had more of the nerve cells that detect the feared scent.
- 3 - Skin electrical conductivity, which rises with sweating, was used to measure fear in the twin study.
- 4 - In the twin study, identical twins reacted more alike to frightening images than fraternal twins did.
Topic Definition
- Transgenerational Epigenetic Inheritance
Transgenerational epigenetic inheritance is the passing of epigenetic marks, chemical tags such as DNA methylation that switch genes on or off without changing the DNA sequence itself, from parents to their children and grandchildren. It may explain how a parent's experiences, such as stress, trauma, diet or learned fear, could affect the traits and health of later generations. It is well documented in plants, worms and mice, but its role in humans is still being studied.
Overview
The Genetic Legacy of Fear: How Phobias May Be Inherited Across Generations
Research suggests that the fears a parent experiences may be passed down to their children. The results of experiments with mice suggest that fallout from a person's traumatic experiences may extend through generations. The study was a particularly interesting one.
Transgenerational epigenetic inheritance is the transmission of epigenetic markers from one organism to the next that affects the traits of offspring without altering the primary structure of DNA. The less precise term "epigenetic inheritance" may cover both cell-cell and organism-organism information transfer. Although these two levels of epigenetic inheritance are equivalent in unicellular organisms, they may have distinct mechanisms and evolutionary distinctions in multicellular organisms.
Parents' stressful experiences can influence an offspring's vulnerability to many pathological conditions, including psychopathologies, and their effects may even endure for several generations. Nevertheless, the cause of this phenomenon has not been determined, and only recently have scientists turned to epigenetics to answer this question.
The Study
Mouse parents learned to associate the smell of cherry blossoms with an electric shock.
The children of these mice and their grandchildren startled in response to the scent, a sign of fear, even though they had never smelled the scent before in their lives. Mice children also had more neurons that detect the cherry blossom smell than mice whose parents were not exposed to the smell.
Sperm cells alone have the ability to deliver the message of fear, according to Kerry Ressler and Brian Dias at Emory University. The DNA in sperm cells was imprinted with the association of fear. A gene that codes for the molecule that detects the smell of cherry blossoms carried a chemical stamp that might have changed its behavior.
Information stemming from parents' experiences might be important in relation to survival.
Being aware that a certain smell signals a rough shock could help an animal avoid trouble without having to experience the shock firsthand. The experiences of our ancestors may be an under-appreciated influence on the brains of both animals and people, as well as our behaviors, according to Kerry and Brian. The discovery shows the multi-generational effects of:
From a scientific perspective this is referred to as, 'Trans-generational Epigenetic Inheritance.' What this means; in essence, is that your environment may affect your genetics in ways that can be passed down to your children. The finding might lead to a completely new understanding of some forms of mental illnesses and could at least partially explain the increasing rates of some disorders.
A Study of Twins and Fear
Fear is something long thought to be a learned response.
Fear actually may be a partly inherited trait, one programmed into our genetic makeup, according to a study of twins. Dr. John Hettema of Virginia Commonwealth University in Richmond, Virginia along with colleagues from Sweden, studied 90 pairs of identical twins and 83 pairs of fraternal, or non-identical twins, enrolled in the Swedish Twin Registry. Identical twins share virtually all of their genes, while fraternal twins share about half, the same as brothers and sisters born separately to the same parents.
In the study, the twins were shown a series of different images. Some of the images were naturally frightening - such as spiders and snakes. Other images were neutral such as triangles and circles. The twins were also given a mild electrical shock as they viewed some of the images.
During the testing, researchers measured the subject's skin electrical conductivity, which usually increases in states of fear and anxiety due to increased output from the person's sweat glands. When the researchers analyzed the results, they found that the identical twins had more similar responses than the non-identical twins.
Traditionally, fear is something that has been thought of as a learned response. A person endures a frightening experience and then learns to be anxious and apprehensive when it happens, or the potential for it to happen again arises. The process is referred to as, 'conditioning.'
Dr. Hettema said:
"Now we can say that the fear conditioning process in humans is controlled, at least to some extent, by genetic factors. Between one-third and one-half of the fear conditioning process appears to be inherited."
Fear is a desirable and natural response to dangerous situations. Yet when a person's fear is out of proportion to the stimulus that caused it, or is debilitating or chronic, a person may be said to be suffering from an anxiety disorder. Understanding the genetic basis of fear could assist future researchers with development of treatments for conditions such as anxiety and phobia states, according to Dr. Hettema.
Thoughts Concerning These Results
It is amazing to find scientists suggesting that people can inherit fears, but it seems the results are what they are. The results of these experiments suggest many things. For example; it is perhaps not so unusual that both a father and son are afraid of spiders, or that a mother and daughter are frightened by snakes - even though they have no real reason to be.
The studies also suggest something far more large scale. For example; children of those who fought in wars may experience the same or similar trauma their parents do. If the studies are proven correct in the long-term, even the grandchildren of those who have endured a war may experience PTSD similar to the PTSD their grandparents do or did.
Is there a, 'compounding,' factor at play? One has to wonder. If the people of a certain nation are repeatedly exposed to shelling, bombing, and other violent military activity - do repeated exposures to such violence, 'compound,' thereby worsening the fears and trauma their children and grandchildren experience? Perhaps one day science will tell us.
More on this topic: Phobias and Fears Publications - Psychological Disorders Publications - Neurological Disorders Publications
Frequently Asked Questions
NOTE: Researched FAQs by Disabled World (DW)
What is the most common phobia?
Specific phobias of animals such as spiders, snakes and dogs are among the most common, along with fears of heights, flying, needles and blood.
Are phobias more common in women?
Yes. Specific phobias are diagnosed about twice as often in women as in men, although the reasons, biological and social, are still debated.
Can a phobia develop without a bad experience?
Yes. Many people with phobias cannot recall a frightening event that started them, which is one reason researchers look at genetic and inherited factors.
What is exposure therapy?
Exposure therapy is a form of cognitive behavioral therapy in which a person faces the feared object or situation gradually and safely until the fear response weakens.
Can children learn fears from watching their parents?
Yes. Children often pick up fears by seeing how parents react to dogs, insects or other situations, which makes it hard to separate learned and inherited fear in families.
Is PTSD passed down to children?
Children of trauma survivors have higher rates of anxiety and PTSD in some studies, but this likely reflects a mix of genes, epigenetics, parenting and shared environment.
What is the difference between a fear and a phobia?
A fear is a normal response to a real threat. A phobia is an intense, lasting fear that is out of proportion to the danger and leads a person to avoid the trigger.
Can medication help with phobias?
Therapy is the main treatment. Some people also benefit from short-term medicines such as beta blockers for performance anxiety or antidepressants for broader anxiety disorders.
Insights, Analysis, and Developments
Editorial Note: Inherited fear is still a young and debated field. The mouse findings are striking, but how strongly epigenetic marks pass between generations in humans is much less certain, and families also share environments, stories and learned habits that shape fear. What the research does suggest is that a tendency toward anxiety or phobias is not a personal failing, and that both biology and experience play a part. The practical message is encouraging: inherited or not, phobias and anxiety disorders respond well to treatment, especially exposure-based cognitive behavioral therapy, and anyone whose fears limit their daily life, work or relationships should speak with a doctor or mental health professional.*
Author Credentials: Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursuing Disability Studies. As a CNA Thomas has provided care for people with all forms of disabilities. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.
* Editorial additions by Ian C. Langtree.