Genetic

If you are diagnosed with SAD, you probably have specific genes that made you more prone to developing the disorder. If you have a first degree relative with SAD, you may also be two to six times more likely to develop the disorder. Heritability is the proportion of variation in a phenotype (trait, characteristic, or physical feature) that is thought to be caused by genetic variation among individuals. The remaining variation is usually attributed to environmental factors. Studies of heritability typically estimate the proportional contribution of genetic and environmental factors to a particular trait or feature. So far, researchers have not found a particular genetic makeup linked to SAD. They have, however, found certain genes linked to other anxiety disorders such as agoraphobia and panic disorder.

Environmental

The psychosocial causes of social anxiety disorder (SAD) include factors in the environment that influence you as you grow up. If one of your parents has social anxiety disorder (SAD), then you are more likely to develop the disorder yourself. This could be due to both genetic and environmental influences. Psychologists have developed theories about how children may become socially anxious through learning. Your upbringing can also impact the likelihood that you will develop SAD. You are more likely to develop the disorder if:

As a child, you were not exposed to enough social situations and were not allowed to develop appropriate social skills.​One or both of your parents was rejecting, controlling, critical, or overprotective. Children that do not form a proper attachment to their primary caregiver are at greater risk because they can’t calm and soothe themselves when in stressful situations.

Behavioral Inhibition in Childhood 

Do you know a toddler or young child who always becomes extremely upset when confronted with a new situation or unfamiliar person? When faced with these types of situations does the child cry, withdraw, or seek the comfort of a parent? This type of behavior in toddlers and young children is known as behavioral inhibition. Children who show behavioral inhibition as a toddler are at greater risk for developing SAD later in life. Because this temperament shows up at such a young age, it is likely an inborn characteristic and the result of biological factors.

Societal

Societal factors that can influence the development of social anxiety include growing up in a culture with a strong collectivistic orientation, such as Japan or Korea. The syndrome taijin kyofusho in these cultures involves a fear of making other people uncomfortable and reflects a culture in which concern for how you fit as part of the larger group is emphasized.

Brain Structure/Biological

Just as x-rays are used to “see inside” your body, the same can be done for your brain. Medical researchers use a technique called “neuroimaging” to create a picture of the brain. Newer techniques can look not only at brain structure but at types of functions in specific regions of the brain. For mental disorders, researchers may look differences in blood flow in specific areas of the brain for people who are known to have a particular disorder. We know that four areas of the brain are involved when you experience anxiety. A study of blood flow in the brain published in 2001 found differences in the brains of social phobics when speaking in public. For this study, they used a type of neuroimaging called “Positron Emission Tomography” (PET). The PET images showed that people with social anxiety disorder had increased blood flow in their amygdala, a part of the limbic system associated with fear. In contrast, the PET images of people without SAD showed increased blood flow to the cerebral cortex, an area associated with thinking and evaluation. It seems that or people with social anxiety disorder, the brain reacts to social situations differently than people without the disorder.

Neurotransmitters

If you have social anxiety disorder, there are likely imbalances of certain chemicals in your brain, known as neurotransmitters. These neurotransmitters are used by your brain to send signals from one cell to another. People with social anxiety disorder have been shown to have some of the same imbalances of these neurotransmitters as people with agoraphobia and panic disorder. Understanding how these brain chemicals relate to social anxiety disorder is important to determine the best medications for treatment.

A Word From Verywell

There is no single cause of SAD. In most people, the disorder is the result of a combination of factors. When receiving a diagnosis or treatment for social anxiety disorder, your doctor or mental health professional should discuss with you possible contributing factors to your social anxiety.