Watch this fantastic breakdown of how positive and negative experiences in early childhood affect the foundation of brain development. This video was created by the Alberta Family Wellness Initiative with help from the Harvard Center on the Developing Child and the Frameworks Institute.
Essentially, it shows that through ongoing back and forth communication between infants and their caregivers, as well as healthy stress, young brains develop the resilience and executive functioning skills required to grow to a successful adulthood.
On the other hand, exposure to toxic stress at a young age can cause irreparable damage to a developing brain. Stressors like abuse, neglect and parental addiction can dramatically undermine social and emotional well being, making it difficult for the child to learn self control, persistence and empathy.