Parenting ‘style’ affects children at a molecular level

Infant with father

How a parent responds to their child’s needs can affect more than just behaviour.

New research from UBC’s faculty of medicine and BC Children’s Hospital Research Institute (BCCHR) reveals that parenting ‘style’ can affect how a child’s genes are expressed—and these biochemical alterations can be observed among infants as young as three months of age.

The study, recently published in Attachment & Human Development, examined how toddler-parent attachment style correlates with the modification of infant DNA. The research team demonstrated that toddlers who formed secure attachments—meaning they used their parent as a secure base for exploration and as a safe haven from stress—had a different molecular profile than toddlers who had formed insecure attachments with their parents.

Dr. Sarah Merrill

Dr. Sarah Merrill

“Although the long-term implications for childhood development and adult health are not yet known, this study illustrates the potential biological consequences of early adversity, but also demonstrates the resilience associated with positive parenting,” says the study’s lead author Dr. Sarah Merrill, a UBC postdoctoral fellow in the Kobor lab.

According to the researchers, attachment between a parent and child forms within the first years of life and, once developed, is usually maintained into—and throughout—adulthood. It’s estimated that roughly half of children develop secure attachments with their parents. The remaining will go on to form a range of insecure attachment ‘styles’—observed in infants whose parents are withdrawn or under-stimulating, intermittently responsive or provoke fear when their child is seeking comfort or safety.

The study involved 93 pairs of children and their mothers. Through a two-way mirror, the researchers observed attachment style at 22 months of age through a series of mother-child separations and reunions, as well as interactions between the child and a stranger. Nearly half of the children who participated in the study were classified as securely attached.

“These molecular differences indicate that positive parenting has potential benefits when it comes to a child’s overall immune system and their cognitive development.”
Dr. Sarah Merrill

The research team then conducted a retroactive analysis of blood samples, originally obtained from the children at three months of age, to determine the extent of a biochemical modification known as DNA methylation, in which some parts of the chromosome are tagged with small molecules made of carbon and hydrogen. These molecules may act as “dimmer switches” that help to control how active each gene is, and thus affect how cells function.

Dr. Michael Kobor

Dr. Michael Kobor

The researchers found significant DNA methylation differences between children who were securely attached compared to those who were not. The changes were observed in DNA sites located in genes associated with the immune system and cognitive development.

“These molecular differences indicate that positive parenting has potential benefits when it comes to a child’s overall immune system and their cognitive development,” says Dr. Merrill.

The researchers plan to continue following the study participants to determine if the molecular changes observed at three months of age remain over time.

“Our hypothesis is that these molecular changes and attachment style both have the potential to be lifelong,” says Dr. Merrill.

This finding builds on earlier work led by Dr. Michael Kobor and colleagues that showed that the simple act of holding infants early in life may associate with deeply-rooted and potentially lifelong patterns on the epigenome.