Infant-Mother First-Year Relationship Predicts Child's Behavior Up to 13 Years

I was surprised to learn from a Science Digest article that the first year of a infant-mother relationship was predictive of the child's conduct later. The study was conducted at the University of Chicago. Within the study, infant temperament was paired with the mother's parenting skills. This study provides additional evidents that a focus on early childhood training could reduce delinquency. While reading the article, I wondered why the prediction ends at 13. Do kids become monsters at 13?