Yes, social anxiety disorder, also known as social phobia, is heritable. In other words, social anxiety disorder runs in families. A recent meta-analysis found that social anxiety disorder (SAD) and social anxiety symptoms (SAS) tend to run in families, and there are both genetic and environmental influences. However, the genetic influence of developing SAD or SAS in adults was half than that in younger people with SAD or SAS (Scaini et al., 2014). This study highlights how social anxiety is disorder has both genetic and environmental contributions, and younger patients have more of a genetic contribution than older patients. So if you develop SAD or SAS as a child, this is more due to heredity, or genetics. If you develop SAD or SAS as an adult, this is less about heredity, and more about environmental influences.
Several other psychiatric disorders are highly heritable. Schizophrenia, bipolar disorder, and autism have an estimated heritability of 80% or higher (Burmeister et al., 2008). Anxiety disorders, such as social anxiety disorder, have more of an environmental influence, but also have a genetic influence. However, having a close relative with a psychiatric disorder, such as social anxiety disorder, is the #1 risk factor to date. Soon, psychiatry may develop objective, biological tests to help diagnose anxiety disorder, such as social anxiety disorder. This may come in the form of genetic testing (DNA analysis) to determine how much of a risk you have to developing social anxiety disorder. However, to date, the gene(s) for social anxiety disorder have not been identified.