Genetic data suggests that shyness is heritable, though environmental factors, such as
child abuse or ridicule contribute to its development. Shyness may precede or result from physical anxiety symptoms, and is distinct from both
social anxiety and
social anxiety disorder.
Genetics and heredity Research indicates a positive correlation between childhood fearfulness and the development of shyness. Some studies suggest that higher levels of cortisol in shy children are associated with increased susceptibility to illness. Several genetic links to shyness are current areas of research.
Mouse models have also been used, to derive genes suitable for further study in humans. One such gene, the
GAD gene, which is involved in producing
GABA (a chemical that helps regulate brain activity and anxiety), has so far been shown to have some association with behavioral inhibition (a tendency to experience distress in new situations). The genetics of shyness involves the study of candidate genes related to dopamine and serotonin regulation. Studies have identified modest correlations between shyness and specific variations of the
DRD4 gene and the
5-HTTLPR (a region of the serotonin transporter gene). However, the influence of these individual genetic markers is considered small, and research into their connection with related conditions, such as social anxiety or obsessive-compulsive disorder, is ongoing. Previous studies had shown a connection between this form of the gene and both obsessive-compulsive disorder and
autism.
Thalia Eley argues that only about 30% of shyness as a trait is genetically inherited, while the rest emerges as a response to the environment.
Mercury poisoning Characteristics such as excessive shyness, embarrassment, and social phobia are associated with
erethism (a neuropsychiatric syndrome resulting from chronic
mercury poisoning).
Prenatal development Evidence suggests an association between day length during pregnancy and the prevalence of shyness. A longitudinal study indicated that shorter day length during the midpoint of gestation may be associated with an increased probability of shyness in childhood.
Low birth weights There is an observed correlation between birth weight and shyness or cautiousness in children. Findings suggest that those born at low birth weights are more likely to be shy, risk-averse and cautious compared to those born at normal birth weights. However, this association does not establish a causal relationship. == Personality trait ==