Children who have the depressive genes are especially sensitive to early neglect, malnutrition, deprivation, physical harm, and psychological abuse, particularly at the ages when their brains are still developing. Studies show that early childhood stress can turn on depressive genes and make children vulnerable to depression. For example, one study showed that individuals who carried depressive genes were more likely to be depressed as adults if they had been abused as children.
Children in hostile environments also develop maladaptive stress-management habits that often continue into adulthood. For example, strategies like denying the existence of problems, withdrawal, and isolation may help children survive hostile environments, but when these once-useful habits persist in adults, they serve no purpose but to cause psychological problems.
Also, children who inherit genes for depression often have parents with unipolar major depression or depressive tendencies. When parents’ depression is severe, it can decrease the effectiveness of their parenting, and stressful family environments are more likely to develop.