Learning and social and emotional experiences have an impact on gene activity, and modify the growth and function of nerve cells. As a result, and depending on the interactive experiences within relationships, motoric, cognitive and emotional skills, as well as behavior of the infant are influenced. If the child fails to experience a dependable relationship, the symptoms of mental disturbance often develop (e.g. ADHD, among others). Further factors that impact on brain development and lead to posttraumatic stress disorder (PTSD) are deprivation, physical violence and sexual abuse in early childhood.