Scientists have discovered perhaps the strongest evidence yet linking variation in a particular gene with anxiety-related traits. Particular versions of a gene that affect the activity of important neurotransmitter receptors were more common in both children and adults assessed as being inhibited or introverted and also were associated with increased activity of brain regions involved in emotional processing. It has long been recognized that the tendency to anxiety disorders can run in families and is believed to be influenced by the interaction of several genes.