Maternal behaviour may reflect in a child’s epigenome

A new study has linked mothers’ neutral behaviour towards infants to a stress-related epigenetic change in children. Epigenetics are molecular processes independent of DNA that influence gene behaviour. In this study, researchers found that a mother’s neutral or awkward behaviour with their babies at 12 months correlated with an epigenetic change called methylation, or the addition of methane and carbon molecules, on a gene called NR3C1 when the children were seven years old.
The gene has been associated with regulating the body’s response to stress. Elizabeth Holdsworth, a Washington State University biological anthropologist and lead author of the study published in the American Journal of Human Biology, said, “There is evidence of a relationship between the quality of maternal-infant interaction and methylation of this gene though these are small effects in response to a relatively small variation in interaction.”
Holdsworth emphasized that the small difference indicated by this study may indicate normal human variation, and it's hard to determine if there are any long-term effects. The authors analyzed a subsample of 114 mother-infant pairs from the Avon Longitudinal Study of Parents and Children, a project that tracks a cohort of children born in 1991 and 1992 in Avon, UK.
They focused on mothers because they are often infants’ primary caregivers. Most of the women in this sample were white, college-educated and from middle-income households. The range of warmth they displayed only varied slightly, with the “coldest” behaviour classified as awkward or neutral, but this is exactly what the researchers hoped to test - if even small differences in social interaction could be linked to an epigenetic change. The observed behaviour was then compared against data from an epigenetic analysis of the children's blood samples at age seven. The researchers found that the mothers showing awkward or neutral behaviour toward their infant correlated with a small increase of methylation on the NR3C1 gene. This gene encodes a receptor regulating the HPA axis -- the interaction between the body's hypothalamus, pituitary and adrenal glands. This axis plays a role in stress response, including the production of the body's primary "stress" hormone, cortisol.
“Within developmental biology, we know humans grow to fit the environment that they're in, which contributes to normal human biological variation. It's not necessarily good or bad," Holdsworth said.