All of our symptoms occur within a human body. Inasmuch as the human body is genetic and comprised of DNA from each of our parents, there are dispositions towards the creation of anxiety that are inherited, just as with dispositions toward the creation of blood pressure or blood sugar in the clinical abnormalities of hypertension or diabetes. I will not focus on the specifics of any genetic disorder involved in anxiety other than to say that population studies indicate that anxiety disorders tend to run in families and that researchers cannot find any single gene responsible for any given anxiety disorder.
Anxiety appears to run along the more polygenic model, meaning that multiple genes and interactions between gene products create the states that go along with anxiety. This pattern makes the visible genetic picture (phenotype) of any given inherited gene structure (genotype) malleable, both to its environmental stimuli and its random interplay of inherited gene products. Environmental interactions can shape any given clinical symptom, much as any organism in biology has its niche. For example, we know that identical twins (from one egg) separated at birth have a higher tendency to have anxiety disorders than fraternal twins (from two eggs) separated at birth. We know that children who have a shy temperament have a higher degree of anxiety disorders in life than children who have an outgoing disposition.
However, we also know that a shy child who grows up in a more gregarious household learns that social interaction can be a safe medium of exchange. These findings suggest that the genetic template of any given person is malleable, based upon the environment in which a child grows up or in which an adult lives or receives treatment. Furthermore, we know that patients with anxiety disorders get better in psychotherapy, meaning that whatever given phenotype of illness they may walk in the door with, they are likely to leave with a different, less intense expression of anxiety. All of these data suggest that the clinical manifestation of anxiety is not unilaterally determined by any person’s genetic structure.