A mother whose child has a naturally fearful temperament may act less nurturing toward the child, triggering a vicious cycle of behavior that reinforces the child's fearfulness and shyness, researchers propose.
In previous work, Dr. Nathan A. Fox of the University of Maryland, College Park, and colleagues found that children carrying one or two short versions of a gene involved in transport of the neurotransmitter serotonin were more likely to be extremely shy at age 7 if their mothers reported little social support. If their mothers had plenty of social support, kids carrying the so-called "shy gene" were at no greater risk of shyness.
But children with two long versions of the serotonin transporter gene -- meaning they were free of the shy gene -- were normally outgoing at age 7 no matter how little social support their mothers received.
The team's latest research, reported in the journal Current Directions in Psychological Science, points to a possible mechanism by which a mother's lack of social support might reinforce a child's tendency toward withdrawn behavior.
Fox and colleagues observed that people carrying two copies of the "shy gene" are more likely to react poorly to stresses in life by becoming depressed or developing other maladaptive behavior, while those who don't carry the gene seem to be somewhat shielded from stress. Individuals with just one copy of the shy gene "fall somewhere in the middle."