A scientific study demonstrated that rat mothering behavior impacts the stress response in their pups. Rats that were born and grew up with attentive mothers showed low activation of stress-response genes later in life, while rats with inattentive mothers had high activation of stress-response genes in the same situation. An additional study that swapped the pups at birth (i.e., rats born to inattentive mothers grew up with attentive mothers and vice versa) showed the same positive effect of attentive mothering. How do genetics and/or epigenetics explain the results of this study?

Epigenetic alterations to DNA control whether or not genes are activated. These alterations are connected to DNA and do not alter the order in which the DNA building blocks are arranged.

By switching the pups at birth, it is demonstrated that the later stress responses of the rats are not explained by the genes inherited from the attentive or inattentive mothers. The methylation of genes that regulate the production of stress receptors in the brain was instead discovered to be a result of the attentive mothering. Thus, epigenetic alterations that restricted the expression of stress-response genes were seen in rats that had received attentive mother care, and the impact persisted over the course of the animals' lifespans.