Research into the causes of social anxiety and social phobia is wide-ranging, encompassing multiple perspectives from neuroscience to sociology. Scientists have yet to pinpoint the exact causes. Studies suggest that genetics can play a part in combination with environmental factors.

Genetic and family factors

It has been shown that there is a two to three fold greater risk of having social phobia if a first-degree relative also has the disorder. This could be due to genetics and/or due to children acquiring social fears and avoidance through processes of observational learning or parental psychosocial education. Studies of identical twins brought up (via adoption) in different families have indicated that, if one twin developed social anxiety disorder, then the other was between 30% and 50% more likely than average to also develop the disorder.[27] To some extent this 'heritability' may not be specific - for example, studies have found that if a parent has any kind of anxiety disorder or clinical depression, then a child is somewhat more likely to develop an anxiety disorder or social phobia.[28] Studies suggest that parents of those with social anxiety disorder tend to be more socially isolated themselves (Bruch and Heimberg, 1994; Caster et al, 1999), and shyness in adoptive parents is significantly correlated with shyness in adopted children (Daniels and Plomin, 1985);

Adolescents who were rated as having an insecure (anxious-ambivalent) attachment with their mother as infants were twice as likely to develop anxiety disorders by late adolescence,[29] including social phobia.

A related line of research has investigated 'behavioural inhibition' in infants – early signs of an inhibited and introspective or fearful nature. Studies have shown that around 10-15% of individuals show this early temperament, which appears to be partly due to genetics. Some continue to show this trait in to adolescence and adulthood, and appear to be more likely to develop social anxiety disorder.[30]

Social experiences

A previous negative social experience can be a trigger to social phobia.[31] [32] perhaps particularly for individuals high in 'interpersonal sensitivity'. For around half of those diagnosed with social anxiety disorder, a specific traumatic or humiliating social event appears to be associated with the onset or worsening of the disorder;[33] this kind of event appears to be particularly related to specific (performance) social phobia, for example regarding public speaking (Stemberg et al., 1995). As well as direct experiences, observing or hearing about the socially negative experiences of others (e.g. a faux pas committed by someone), or verbal warnings of social problems and dangers, may also make the development of a social anxiety disorder more likely.[34] Social anxiety disorder may be caused by the longer-term effects of not fitting in, or being bullied, rejected or ignored (Beidel and Turner, 1998). Shy adolescents or avoidant adults have emphasised unpleasant experiences with peers[35] or childhood bullying or harassment (Gilmartin, 1987). In one study, popularity was found to be negatively correlated with social anxiety, and children who were neglected by their peers reported higher social anxiety and fear of negative evaluation than other categories of children.[36] Socially phobic children appear less likely to receive positive reactions from peers[37] and anxious or inhibited children may isolate themselves.[38]