UNC study: Parenting can override effect of genes in how babies respond...(and their infants playing together for 1...),Health

Propper said the study found both genes and parenting were important to the development of how infants' brains help regulate cardiac responses to stress.

At 3 and 6 months old, infants with the form of the dopamine gene associated with risky behaviors did not display a decrease in vagal tone when stressed, while those with the non-risk version of the gene did. At these early ages, it did not appear to matter whether mothers were sensitive or not, Propper said.

However, by the time the infants were 12 months old, the pattern changed. Infants with the risk form of the gene whose mothers were highly sensitive now showed the expected cardiac response when under stress while those with the at-risk gene form who had insensitive mothers did not.

Propper said the findings suggest that although genes play a role in the development of physiological responses to stress, environmental experiences such as mothers' sensitive care-giving behavior can have a strong influence, enough to change the effect that genes have on physiology very early in life.

"Our findings provide further support for the notion that the development of complex behavioral and physiological responses is not the result of nature or nurture, but rather a combination of the two," Propper said. "They also illustrate the importance of parenting not just for the development of children's behavior, but for the underlying physiological mechanisms that support this behavior.

"Infancy is an important time for developing behavioral and biological processes. Although these processes will continue to change over time, parenting can have important positive effects even when children have inherited a genetic vulnerability to problematic behaviors," Propper said.

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