Here's a reminder of the effect of unhappy homes on the brain. Using a questionnaire that identified young adults on the basis of a childhood history of family stress (felt unloved, insulted, put down, threatened, grabbed, shoved, verbally or physically abused, observed quarreling parents or violence between family members), researchers found profound differences in the ways 'stressed' subjects responded to pictures of threat or fear.
Subjects who had unhappy or significantly stressed homes had blunted emotional responses as seen by the activation of their amygdalae. Growing up in oppressive home seems leave some residue in the neurochemistry.
Family Stress and fMRI