Our experiences in life don't just affect how we learn and behave, they can also mark our genes and influence our children, a growing body of research suggests.
Stressful events and drug use appear to alter how and when genes are turned off and on. Some environmental influences create such long-lasting and significant biological changes that they can be passed on to affect the health of the next generation, studies have shown. They don't appear to alter the genes themselves.
Not all of our roughly 20,000 genes—which contain the information that tells the body's cells what to do—are called on to be active, or expressed, at any one time. In a phenomenon known as epigenetics, environmental influences alter whether particular genes are activated. For example, one way that smoking appears to increase the risk of cancer is by deactivating a specific tumor-suppression gene.
Increasingly, scientists are looking for epigenetic changes to help explain how factors like poor parenting and stress in early life degrade physical and mental health later on.
"We want to know how experiences really influence the brain," says Marilyn Essex, a professor of psychiatry at the University of Wisconsin's school of medicine and public health in Madison. "What are some of the underlying biological mechanisms that can help us understand how we get from the early stress to the later health outcomes?"
Scientists say epigenetic signatures might someday be used to predict people's risk of developing disease. Such patterns also might aid clinicians in diagnosing certain conditions, including psychiatric disorders, earlier or more accurately than by relying on observable symptoms alone.