In the report "Negative Parenting Style Contributes to Child Aggression" for Psych Central, Rick Nauert, Ph.D., reports that researchers at the University of Minnesota found that the explosive kindergarteners studied had poor relationships with their mothers from an early age. The researchers concluded that bad parenting during infancy contributed to childhood aggression. The mothers studied handled their children “roughly,” expressed negative feelings towards their kids and had escalating conflicts with them. The researchers concluded that negative parenting caused the children studied to demonstrate "higher levels of anger," which made the mothers more hostile. What was not studied was the relationship between the mother and the father, and how that might have influenced the mother's feelings or behavior.