Abstract: Shyness refers to, discomfort and/or inhibition in social situations that interferes one's pursuing for interpersonal or professional goals. It often manifests as excessive self-focus, preoccupation with one's thoughts, and a variety of emotional and physiological responses. Recent years have witnessed the upsurge of behavioural genetic approach in the study of the causes of shyness. Findings from both twins studies and molecular genetics studies have demonstrated that shyness has important genetic underpinnings, with particularly strong associations with the short gene 5-HTTLPR. Shyness is the consequence of the complex interactions between genes and also between genes and environment.

Key words: shyness, behavioral genetics, molecular genetics, gene, 5-HTTLPR