background Much of the research is focused on the role that genetic factors play in the development of psychiatric disorders during childhood and adolescence.
aim To present an overview of the heritability of these disorders and to describe the current state of the search for specific genetic variants.
method The results of (mainly) Dutch studies in this area are summarised.
results It is estimated that about 60-70% of externalising symptoms and about 40-50% of internalising symptoms are heritable. No genes have yet been identified which influence psychiatric disorders in children. It is clear, however, that even in children, psychiatric symptoms are polygenic, i.e. influenced by many genetic variants, each having a small effect.
conclusion Research on the role of genetic factors is advancing rapidly even in child psychiatry. When sample sizes are enlarged, it should be possible to identify genetic variants.