Genetic aspects of childhood behavioral disorders.

The evidence is reviewed to support the concept that many disruptive, childhood and adolescent behavioral disorders including ADHD, Tourette syndrome, learning disabilities, substance abuse, oppositional defiant disorder and conduct disorder, are part of a spectrum of inter-related behaviors that have a strong genetic component, are polygenically inherited, share a number of genes in common that affect dopamine, serotonin and other neurotransmitters, and are transmitted from both parents. Some of the implications of this hypothesis in relation to diagnosis and treatment are reviewed, including the possibility that the genes involved may be increasing in frequency.