A study conducted to determine the frequency of genetic mutations involving specific genes - namely, glutamate receptor metabotropic (GRM) network genes - found that more than 20% of children and adolescents with ADHD carried the mutations. "Our work shows that ADHD is likely due to genes. It's not due to parenting, not due to some environmental causes," principal investigator Josephine Elia, MD, from Nemours/Alfred L. du Pont Hospital for Children, Wilmington, Delaware, told Medscape Medical News.