According to stress theories there is a tendency for a person’s genetic makeup to predispose them to depression; a negative life experience can trigger a depression. Most studies focus on either the genetics or environment, but not both.

Gerald Haeffel, psychologist, University of Notre Dame, decided to investigate whether a gene associated with dopamine interacted with maternal parenting style to predict episodes of depression. The study consisted of 177 male adolescents from a juvenile detention center in Russia. These participants were ideal candidates for the study because depression rates rise dramatically during this period in life. Using a structured diagnostic interview, to diagnose depression, and a questionnaire to access aspects of maternal parental rearing (i.e. physical punishment, hostility, lack of respect for the child’s point-of-view, and unjustified criticism in front of others).

Neither the genetic or environment factors predicted depression, but the participants with especially rejecting mothers and a specific form of the dopamine transporter gene were at higher risk for major depression and suicidal ideation.