Research has shown that a new mom’s oxytocin levels can influence her behavior, and as a result, the bond she makes with her baby. Now a new epigenetic study suggests that a mom’s behavior can also have a substantial impact on her child’s developing oxytocin system.
Oxytocin is a vital hormone involved in social interaction and bonding in humans. It strengthens trust and closeness in relationships and can be triggered by eye contact, empathy or pleasant touch.
“It is well known that oxytocin is actively involved in early social, perceptual, and cognitive processes, and that it influences complex social behaviors,” says Tobias Grossmann from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig, Germany.
“However, in this study we ask whether the mother’s behavior might also have a decisive influence on the development of the baby’s oxytocin system itself. Advances in molecular biology, epigenetics in particular, have recently made it possible to investigate the interaction of nature and nurture, in this case infant care, in fine detail. That is exactly what we’ve done here.”
For the study, the researchers observed a free play interaction between mothers and their five-month-old babies.
“We collected saliva samples from both the mother and the infant during the visit and then a year later, when the child was 18 months old,” said Kathleen Krol, a Hartwell postdoctoral fellow at the University of Virginia who conducted the study with Grossmann in Leipzig.
“We were interested in exploring whether the involvement of the mother, in the original play session, would have an influence on the oxytocin receptor gene of the child, a year later. The oxytocin receptor is essential for the hormone oxytocin to exert its effects and the gene can determine how many are produced.”
The findings show that epigenetic changes had occurred in infant’s DNA, and that this change was predicted by the quality of the mother’s involvement in the play session.
“If mothers were particularly involved in the game with their children, there was a greater reduction in DNA methylation of the oxytocin receptor gene one year later,” said Krol.
“Decreased DNA methylation in this region has previously been associated with increased expression of the oxytocin receptor gene. Thus, greater maternal involvement seems to have the potential to upregulate the oxytocin system in human offspring.”
“Importantly, we also found that the DNA methylation levels reflected infant temperament, which was reported to us by the parents. The children with higher methylation levels at 18-months, and presumably lower levels of oxytocin receptor, were also more temperamental and less well balanced.”
The study results provide a striking example of how we are not simply bound by our genes but are rather the products of a delicate interplay of nature vs. nurture. Early social interaction with our caregivers can influence our biological and psychological development through epigenetic changes to the oxytocin system.
These and related findings emphasize the importance of parenting in promoting multi-generational health.