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 at least to 1988.

Some research has indicated that shyness and aggression are related—through long and short forms of the gene DRD4, though considerably more research on this is needed. Further, it has been suggested that shyness and 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. In some research, "behavioral inhibition" is studied, in others anxiety or social inhibition is. One solution to this problem is to study the genetics of underlying traits, such as "anxious temperament."

Several genetic links to shyness are current areas of research. One of the most promising is the serotonin transporter promoter region polymorphism (5-HTTLPR), the long form of which has been shown to be highly correlated with shyness in grade school children. Previous studies had shown a connection between this form of the gene and both obsessive-compulsive disorder and autism. Mouse models have also been used, to derive genes suitable for further study in humans; one such gene, the glutamic acid decarboxylase gene (which encodes an enzyme that functions in GABA synthesis), has so far been shown to have some association with behavioral inhibition. 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. The long version of the 5-HTT gene-linked polymorphic region (5-HTTLPR) is now postulated to be correlated with shyness, but in the 1996 study, the short version was shown to be related to anxiety-based traits. This confusion and contradiction does not oppose the genetic basis of personality traits, but does emphasize the amount of research there is still to be done before the bases of even one or two of these characteristics can be identified.