Cora writes: While Adrienne’s mother Charlotte has dementia, the other characters (specifically Lorrie, Adrienne, and Hugh) wonder if her behavior might also be tied to David’s own mental illness, and each expresses the fear that perhaps such illness “runs in the family.” [Adrienne is concerned for Victoria’s mental health.]

[Conversations with friends have] led to our discussion about the familial tendencies and genetic transmission of traits that contribute to specific psychological behaviors. A friend is doing research on epigenetics, specifically looking at how the trauma of ancestors affects the chemical and psychological makeup of their descendants [consider grandchildren who suffer anxiety disorders, might this be related to their grandparents’ Holocaust trauma?].

Detailed information about inheritable mental illness can be found at The Encyclopedia of Mental Disorders’ page: Genetic Factors and Mental Disorders. Below, some excerpts:

SCHIZOPHRENIA. Researchers have known for many years that first-degree biological relatives of patients with schizophrenia have a 10% risk of developing the disorder, as compared with 1% in the general population. The identical twin of a person with schizophrenia has a 40%–50% risk.

At present, genetic factors are thought to account for about 40% of a person’s risk of depression, with environmental factors and personal temperament accounting for the remaining 60%.

With regard to manic depression, twin studies have shown that the twin of a patient diagnosed with manic depression has a 70%–80% chance of developing the disorder. As of January 2002, a team of German researchers studying 75 families with a total of 275 members diagnosed with manic depression (out of 445 persons) has narrowed its search for genes for manic depression to one locus on human chromosome 10 and another on the long arm of chromosome 8.

ANXIETY DISORDERS. It has been known for some time that anxiety disorders tend to run in families. Recent twin studies as well as the ongoing mapping of the human genome point to a genetic factor in the development of generalized anxiety disorder (GAD). One study determined the heritability of GAD to be 0.32.

Recent research has also confirmed earlier hypotheses that there is a genetic component to agoraphobia, and that it can be separated from susceptibility to panic disorder (PD). In 2001 a team of Yale geneticists reported the discovery of a genetic locus on human chromosome 3 that governs a person’s risk of developing agoraphobia. Panic disorder was found to be associated with two loci, one on human chromosome 1 and the other on chromosome 11q. The researchers concluded that agoraphobia and PD are common, heritable anxiety disorders that share some but not all of their genetic loci for susceptibility.

Here, a super casual shorthand site, that agrees with the information above, without all the science…

Is Mental Illness Genetic? The Mental Disorders You’re Most Likely To Inherit