Question: What do you think triggers/causes a mental disorder?

William Davies answered on 21 Jun 2010:

There are many different ways in which a mental disorder can be triggered. These can be roughly divided into the effects of genes, the effect of environment, and the interaction between genes and environment. We know that genes are important in that i) identical twins (who have the same genes) are more likely to share a mental disorder than non-identical twins (who only share 50% of their genes), ii) mental disorders run in families, and even family members without the actual disorder show some slight signs iii) children that are adopted away from their blood family are at the same risk of developing mental disorders than those that aren’t. We also know that certain environmental factors may predispose to mental disorders, notably, smoking during pregnancy may affect the developing baby, particular viruses and drug taking (including smoking strong cannabis over prolonged periods). If you inherit s particular set of genes that might predispose you to developing a mental disorder, and you are exposed to one or more environmental risk factors, your changes of developing a mental disorder are relatively high.