Schizophrenia

Degree of Relationship To Person with Schizophrenia My risk of developing Schizophrenia My chance of not developing Schizophrenia
No genetic relationship (base rate) 1% 99%
Niece, Nephew, Aunt, Uncle 2% 98%
Grandmother or Grandfather 3% 97%
Brother or Sister 10% 90%
Mother or Father 13% 87%
Both parents 37 to 46% 63 to 54%
Identical Twin 50% 50%

 

Mood Disorder (unipolar depression or bipolar disorder)

Degree of Relationship To Person with Mood Disorder My risk of developing a Mood Disorder My chance of not developing a Mood Disorder
Brother or Sister with Unipolar Depression 15% 85%
Brother or Sister with Bipolar 12% 88%
Mother or Father with Unipolar Depression 15% 85%
Mother or Father with Bipolar 27% 73%
Both parents with Bipolar 74% 26%
Identical Twin with Unipolar Depression 70% 30%
Identical Twin with Bipolar 74% 26%

Source:   Torrey, 1995.

Note:  Statistics cannot be used to predict the course of individual lives.  They can be used as a risk guide, but they do not evaluate any one person's case.  Any statement about risk is done on an actuarial basis in a similar way insurance companies compile lists of features about people at risk for automobile accidents.