As part of Battaglia’s study, he collected saliva samples from his 49 subjects and analyzed their DNA, looking for something that might further explain his results. The shy children, he found, had one or two shorter copies of a gene that codes for the flow of the brain chemical serotonin, a neurotransmitter that plays a role in anxiety, depression and other mood states. Battaglia’s lab is not the only one to have linked this gene to shyness, and while nobody pretends it’s the entire answer, most researchers believe it at least plays a role. “People who carry the short variant of the gene are, in general, a little more shy and reactive to stress,” says psychiatrist Michael Meaney of McGill University in Montreal, who just completed a two-year study of timidity and stress.
Something I’ve never been entirely clear on is, what is the relationship between shyness and mood states like depression and anxiety? Maybe this is still an open question, but they seem to be linked in some way. I guess in a sense shyness is a kind of anxiety, but shy behavior has a very different character from an anxiety attack.