In infancy, genes are the key influence on a child’s ability to deal with stress.
But as early as 6 months of age, parenting plays an important role in changing the impact of genes that may put infants at risk for responding poorly to stress.
The researchers looked at 142 infants who had been placed in a stressful situation—being separated from their mothers—when they were 3, 6, and 12 months old.
They measured infants’ heart rates while they were exposed to the stressor, isolating a cardiac response called vagal tone.
Vagal tone acts like a brake on the heart when the body is in a calm state, but during a challenging situation, this brake is withdrawn, allowing heart rate to increase so the body can actively deal with the challenge.
They also collected DNA to determine which form of a dopamine receptor gene the infants carried; specific forms of this gene are related to problems in adolescence and adulthood including aggression, substance abuse, and other risky behaviors.
To assess the mothers’ behavior as high or low in sensitivity, they also videotaped the mothers and their infants playing together for 10 minutes when the babies were 6 months old.
Both genes and parenting were found to be important to the infants’ development of the way in which the brain helps regulate cardiac responses to stress.
Read more at ScienceDaily