Epigenetics refers to environmental factors at play in the brain’s development. The changes that affect the way your genes work are called epigenetics. DNA methylation is a critical regulatory mechanism referred to in epigenetics. DNA methylation affects the brain’s development, how we learn, memory, and diseases in the human brain. Though epigenetic changes are brought on in infancy by stress, the changes are reversible. Various studies with rats show that baby rats with high-licking mothers have babies with increased DNA methylation. The babies with low licking mothers had lowered methylation, higher autoimmune disease, and less tolerance to stress. When rats who had been neglected were put with moms that were more affectionate, those rats increased their DNA Methylation and developed a higher tolerance to stress.[63] In a human comparison, this is a biological description of a contact interruption between mother and child. A contact interruption, biologically speaking, is a central nervous system alteration. This alteration may persist into adulthood, albeit in modified or attenuated forms, because of maturation and adaptation to decreased volumes in the corpus callosum resulting from developmental trauma.[64] 

 

The behavioural and biological features that distinguish those with interrupted interpersonal contact from others are: high levels of aggression; aggression or fear at neuroendocrine levels; higher levels of cortisol, Nero-transmitter metabolism, and lower levels of serotonin; and abnormalities in brain structure and function in the gene expression, such as methylation patterns.[65] Socially speaking, the individual has partially blocked their awareness of details in interpersonal relationships to feel safe.