A new study suggests that children's temperament may be due in part to a combination of a certain gene and a specific pattern of brain activity.
So people finding it difficult to soothe their babies need not worry about their parenting skills anymore.
Writing about their findings in the journal Psychological Science, McMaster University researcher Louis Schmidt points out that the pattern of brain activity in the frontal cortex of the brain has been associated with various types of temperament in children.
He highlights the fact that infants who have more activity in the left frontal cortex are characterized as temperamentally "easy" and are easily calmed down, while those with greater activity in the right half of the frontal cortex are temperamentally "negative" and are easily distressed and more difficult to soothe.
In the current study, he and his colleagues focused on the interaction between brain activity and the DRD4 gene to see whether it predicted children's temperament.
According to background information in the Psychological Science article, previous studies have linked the longer version of this gene to increased sensory responsiveness, risk-seeking behavior, and attention problems in children.
In the present study, brain activity was measured in 9-month-old infants through electroencephalography (EEG) recordings. When the children were 48 months old, their mothers completed questionnaires regarding their behavior and DNA samples were taken from the children for analysis of the DRD4 gene.
Schmidt says that the results reveal interesting relations among brain activity, behavior, and the DRD4 gene.
He says that among the children with more activity in the left frontal cortex at 9 months, those who had the long version of the DRD4 gene were more soothable at 48 months than those who possessed the shorter version of the gene.
However, he adds, the children with the long version of the DRD4 gene, who had more activity in the right frontal cortex, were the least soothable and exhibited more attention problems compared to the other children.
Schmidt says that these findings suggest that the long version of the DRD4 gene may act as a moderator of children's temperament.
"(The) results suggest that it is possible that the DRD4 long allele plays different roles (for better and for worse) in child temperament (depending on internal conditions or the environment inside their bodies)," note the authors.
They conclude that the pattern of brain activity, that is, greater activation in left or right frontal cortex-may influence whether this gene is a protective factor or a risk factor for soothability and attention problems.
The authors cautioned that there are likely other factors that interact with these two measures in predicting children's temperament.