You will have heard of the nature-nurture debate. In the last decade researchers have come to a deeper understanding of how the two interact. The field is called epigenetics and there is an interesting example of this in the link between stress and attachment.

Research has shown that rats who have been raised by mothers who groom and lick them are later better able to cope with stress than pups who were infrequently licked and groomed. What appears to happen is that the brains of well-licked baby rats have been changed. There are receptors in the brain that mop up the stress hormone cortisol, reducing the effect of stress on the brain. The gene that codes for these receptors is modified by the mothers’ behaviour so that ‘unlicked’ pups ultimately have fewer cortisol receptors in their brain.

The bottom line is that the attachment behaviours of the mother appears to alter the young rats’ brains so they cope less well with stressful experience. And this also affects the way the young rats subsequently treat their own babies. Nurture modifies nature. Poor attachment experiences have negative effects.