Mental health and genes phone in
During 2012, BBC Radio Cornwall will continue running a series of phone-ins about mental health.
On 7 November, Laurence Reed and a team of experts discussed mental health and genes.
Some illnesses are known to be caused by a problem with a specific gene.
The Cornwall Partnership NHS Foundation Trust said that mental disorders such as schizophrenia, bipolar affective disorder and depression can run in families, but no singular gene was responsible for causing this and there was not a clear understanding of how they were inherited.
If a parent has suffered from severe depression, then a son or daughter is about eight times more likely to become depressed themselves.
Women are twice as likely to be diagnosed with depression, but this may be due to women being generally more likely to talk about their problems.
Schizophrenia affects about one in every 100 people over the course of their life. One in 10 of those people will have a parent with the illness.
It affects men and women equally and seems to be more common in city areas and in some ethnic minority groups.
The risk of developing the disorder increases with the number of family members who have it and how closely they are related. If one identical twin has schizophrenia, their twin has about a 50% chance of having it too.
If one non-identical twin/sibling has schizophrenia, then the other twin will have about a 10-15% chance of developing it.
The programme was broadcast on 7 November on BBC Radio Cornwall. It will be available on listen again for seven days.