Technology always produces new directions for research, and when it became possible to do genetic testing, psychiatry became committed to finding the genetic causes of mental illness. Finding a genetic link seemed particularly relevant for schizophrenia, a fairly common (affecting about 1 percent of the population), severe, and perplexing form of mental illness and one that clearly runs in families. And yet after thirty years and millions upon millions of dollars’ worth of research, we have failed to find consistent genetic patterns for schizophrenia – or for any other psychiatric illness, for that matter. Some of my colleagues have also worked hard to discover genetic factors that predispose people to develop traumatic stress. That quest continues, but so far it has failed to yield any solid answers.
Recent research has swept away the simple idea that “having” a particular gene produces a particular result. It turns out that many genes work together to influence a single outcome. Even more important, genes are not fixed; life events can trigger biochemical messages that turn them on or off by attaching methyl groups, a cluster of carbon and hydrogen atoms, to the outside of the gene (a process called methylation), making it more or less sensitive to messages from the body. While life events can change the behavior of the gene, they do not alter its fundamental structure. Methylation patterns, however, can be passed on to offspring – a phenomenon know as epigenetics. Once again, the body keeps the score, at the deepest levels of the organism.
Bessel van der Kolk – The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma p.151