Woman holding a child shown at two ages, infant and toddler, superimposed on one another

A new study from the University of Virginia’s Department of Psychology offers evidence to suggest how experience in infancy could affect gene expression in a developing child. The research field of epigenetics examines how environmental factors, from diet to family dynamics, might affect how or to what degree particular genes are “switched on” or “switched off.” In a study published in Science Advances, a research team led by Dr. Kathleen Krol found evidence to suggest that when mothers actively engage with their infants, there is a positive effect on expression of the infant’s oxytocin receptor gene.

As Krol explains, oxytocin—sometimes informally referred to as the “love” or “bonding” hormone—is an important regulator of healthy social behaviors, such as how we perceive emotions, how empathetic we are and how much we trust others. In the study, Krol and her team observed mothers and babies interacting at 5 months. They also took saliva samples from both mother and baby at that time, and then again when the babies were 18 months old, examining these samples for a chemical modification—known as “DNA methylation”—on the oxytocin receptor gene. Animal studies, Krol says, have shown that “the greater amount of DNA methylation on a gene, the less expression of that gene.” The researchers found that the more engaged mothers were with their infants at 5 months, “the greater the reduction in DNA methylation the infant showed one year later,” Krol says. 

With a large body of research demonstrating the connection between early caregiving environment and healthy child development, Krol’s research suggests a potential biological mechanism, she says, for “how the mom’s behavior is impacting how her infant’s oxytocin system is developing.”