Editing Shyness (section)

== Origins ==

The initial cause of shyness varies. Scientists believe that they have located genetic data supporting the [[hypothesis]] that shyness is, at least, partially genetic. However, there is also evidence that suggests the environment in which a person is raised can also be responsible for their shyness. This includes [[child abuse]], particularly [[emotional abuse]] such as ridicule. Shyness can originate after a person has experienced a physical [[anxiety]] reaction; at other times, shyness seems to develop first and then later causes physical symptoms of anxiety. Shyness differs from both [[social anxiety]] and [[social anxiety disorder]], which is a narrower, often [[clinical depression|depression]]-related psychological condition including the experience of [[fear]], apprehension or worrying about being evaluated by others in social situations to the extent of inducing [[panic]].{{cn|date=March 2025}}

Shyness may come from genetic traits, the environment in which a person is raised and personal experiences. Shyness may be a [[personality trait]] or can occur at certain stages of development in children.

=== Genetics and heredity ===

Shyness is often seen as a hindrance to people and their development. The cause of shyness is often disputed but it is found that [[fear]] is positively related to shyness,<ref>{{cite journal |doi=10.1080/15250000902839971 |title=Development of Shyness: Relations with Children's Fearfulness, Sex, and Maternal Behavior |year=2009 |last1=Eggum |first1=Natalie |last2=Eisenberg |first2=Nancy |last3=Spinrad |first3=Tracy |last4=Reiser |first4=Mark |last5=Gaertner |first5=Bridget |last6=Sallquist |first6=Julie |last7=Smith |first7=Cynthia |journal=Infancy |volume=14 |issue=3 |pages=325–345 |pmid=20011459 |pmc=2791465}}</ref> suggesting that fearful children are much more likely to develop being shy as opposed to children less fearful. Shyness can also be seen on a biological level as a result of an excess of [[cortisol]]. When cortisol is present in greater quantities, it is known to suppress an individual's immune system, making them more susceptible to illness and disease.<ref>{{cite journal |doi=10.1037/h0087100 |title=Shyness and symptoms of illness in young children |year=2000 |last1=Chung |first1=Joanna Y. Y. |last2=Evans |first2=Mary Ann |journal=Canadian Journal of Behavioural Science |volume=32 |pages=49–57}}</ref> The genetics of shyness is a relatively small area of research that has been receiving an even smaller amount of attention, although papers on the biological bases of shyness date back to 1988. Some research has indicated that shyness and [[aggression]] are related—through long and short forms of the [[gene]] [[Dopamine receptor D4|DRD4]], though considerably more research on this is needed. Further, it has been suggested that shyness and [[social anxiety|social phobia]] (the distinction between the two is becoming ever more blurred) are related to [[obsessive-compulsive disorder]]. As with other studies of [[behavioral genetics]], the study of shyness is complicated by the number of genes involved in, and the confusion in defining, the [[phenotype]]. Naming the phenotype – and translation of terms between genetics and [[psychology]] — also causes problems.

Several genetic links to shyness are current areas of research. One is the [[serotonin]] transporter promoter region polymorphism ([[5-HTTLPR]]), the long form of which has been shown to be modestly correlated with shyness in grade school children.<ref name="ArbelleS2003Relation">{{Cite journal |first1=Shoshana |last1=Arbelle |first2=Jonathan |last2=Benjamin |first3=Moshe |last3=Golin |first4=Ilana |last4=Kremer |first5=Robert H. |last5=Belmaker |first6=Richard P. |last6=Ebstein |title=Relation of shyness in grade school children to the genotype for the long form of the serotonin transporter promoter region polymorphism |journal=[[American Journal of Psychiatry]] |volume=160 |issue=4 |pages=671–676 |date=April 2003 |pmid=12668354 |doi=10.1176/appi.ajp.160.4.671}}</ref> Previous studies had shown a connection between this form of the gene and both obsessive-compulsive disorder and [[autism]].<ref>{{cite journal |pmid=17151167 |year=2006 |last1=Brune |first1=CW |last2=Kim |first2=SJ |last3=Salt |first3=J |last4=Leventhal |first4=BL |last5=Lord |first5=C |last6=Cook Jr |first6=EH |title=5-HTTLPR Genotype-Specific Phenotype in Children and Adolescents with Autism |volume=163 |issue=12 |pages=2148–56 |doi=10.1176/ajp.2006.163.12.2148 |journal=The American Journal of Psychiatry }}</ref> [[Model organism#Vertebrates|Mouse model]]s have also been used, to derive genes suitable for further study in humans; one such gene, the [[L-glutamic acid decarboxylase|glutamic acid decarboxylase]] gene (which encodes an [[enzyme]] that functions in [[Gamma-aminobutyric acid|GABA synthesis]]), has so far been shown to have some association with behavioral inhibition.<ref>{{cite journal |last1=Smoller |first1=Jordan W. |last2=Rosenbaum |first2=Jerold F. |last3=Biederman |first3=Joseph |last4=Susswein |first4=Lisa S. |last5=Kennedy |first5=John |last6=Kagan |first6=Jerome |last7=Snidman |first7=Nancy |last8=Laird |first8=Nan |last9=Tsuang |first9=Ming T. |last10=Faraone |first10=Stephen V. |last11=Schwarz |first11=Alysandra |last12=Slaugenhaupt |first12=Susan A. |title=Genetic association analysis of behavioral inhibition using candidate loci from mouse models |journal=American Journal of Medical Genetics |year=2001 |volume=105 |pages=226–235 |doi=10.1002/ajmg.1328 |pmid=11353440 |issue=3 }}</ref>

Another gene, the dopamine D4 receptor gene (DRD4) exon III polymorphism, had been the subject of studies in both shyness and aggression and is currently the subject of studies on the "novelty seeking" trait. A 1996 study of anxiety-related traits (shyness being one of these) remarked that, "Although twin studies have indicated that individual variation in measures of anxiety-related personality traits is 40-60% heritable, none of the relevant genes has yet been identified", and that "10 to 15 genes might be predicted to be involved" in the anxiety trait. Progress has been made since then, especially in identifying other potential genes involved in personality traits, but there has been little progress made towards confirming these relationships.<ref>{{cite journal |last1=Lesch |first1=Klaus-Peter |last2=Bengal |first2=Dietmar |last3=Heils |first3=Armin |last4=Sabol |first4=Sue Z. |last5=Greenberg |first5=Benjamin D. |last6=Petri |first6=Susanne |last7=Benjamin |first7=Jonathan |last8=Muller |first8=Clemens R. |last9=Hamer |first9=Dean H. |last10=Murphy |first10=Dennis L. |title=Association of anxiety-related traits with a polymorphism in the serotonin transporter gene regulatory region |journal=Science |year=1996 |volume=274 |issue=5292 |pages=1527–1531 |bibcode=1996Sci...274.1527L |doi=10.1126/science.274.5292.1527 |pmid=8929413|s2cid=35503987 }}</ref> The long version of the 5-HTT gene-linked polymorphic region (5-HTTLPR) is now postulated to be correlated with shyness,<ref name="ArbelleS2003Relation"/> but in the 1996 study, the short version was shown to be related to anxiety-based traits.

[[Thalia C. Eley|Thalia Eley]], professor of developmental behavioural genetics at [[King's College London]], argues that only about 30% of shyness as a trait is genetically inherited, while the rest emerges as a response to the environment.<ref>{{cite web |first=Sarah |last=Keating |title=The science behind why some of us are shy |publisher=BBC Future|date=5 June 2019 |url=http://www.bbc.com/future/story/20190604-the-science-behind-why-some-of-us-are-shy |access-date=6 June 2019 }}</ref>

=== As a symptom of mercury poisoning ===

Excessive shyness, embarrassment, self-consciousness and [[timidity]], social-phobia and lack of self-confidence are also components of [[erethism]], which is a symptom complex that appears in cases of [[mercury poisoning]].<ref>WHO (1976) Environmental Health Criteria 1: Mercury, Geneva, [[World Health Organization]], 131 pp.</ref><ref>WHO. Inorganic mercury. Environmental Health Criteria 118. World Health Organization, Geneva, 1991.</ref>

=== Prenatal development ===

The prevalence of shyness in some children can be linked to day length during [[pregnancy]], particularly during the midpoint of prenatal development.<ref name=daylength>Gortmaker, SL. et al. ''Daylength during pregnancy and shyness in children: results from northern and southern hemispheres''. 1997.</ref> An analysis of longitudinal data from children living at specific latitudes in the [[United States]] and [[New Zealand]] revealed a significant relationship between hours of day length during the midpoint of pregnancy and the prevalence of shyness in children. "The odds of being classified as shy were 1.52 times greater for children exposed to shorter compared to longer daylengths during gestation."<ref name=daylength /> In their analysis, scientists assigned conception dates to the children relative to their known birth dates, which allowed them to obtain random samples from children who had a mid-gestation point during the longest hours of the year and the shortest hours of the year (June and December, depending on whether the cohorts were in the United States or New Zealand).

The longitudinal survey data included measurements of shyness on a five-point scale based on interviews with the families being surveyed, and children in the top 25th percentile of shyness scores were identified. The data revealed a significant co-variance between the children who presented as being consistently shy over a two-year period, and shorter day length during their mid-prenatal development period. "Taken together, these estimates indicate that about one out of five cases of extreme shyness in children can be associated with gestation during months of limited daylength."<ref name=daylength />

=== Low birth weights ===

In recent years correlations between birth weight and shyness have been studied. Findings suggest that those born at low birth weights are more likely to be shy, risk-aversive and cautious compared to those born at normal birth weights. These results do not however imply a cause-and-effect relationship.<ref name=Us.health>{{cite news|last=U.S|first=News Staff|title=Do Underweight Newborns Make for Shy Adult|url=http://health.usnews.com/health-news/family-health/articles/2008/07/09/do-underweight-newborns-make-for-shy-adults|access-date=14 March 2013|date=9 July 2008}}</ref>