Certain fears arising in response to the environment may be passed from generation to generation without changes in the genetic sequence.
This could have implications for families suffering from cycles of drug addiction, neuropsychiatric illness and other behavioral prsoblems, but so far the research has only been done in mice, and the results remain controversial.
In a 2014 study published in Nature Neuroscience, researchers found that the offspring of mice trained to associate electric shocks with the smell of acetophenone—a chemical with a scent similar to cherries and almonds—also displayed signs of fear when exposed to the chemical. This occurred even though the offspring had never experienced that scent before.
The next generation—the “grandchildren” of the mice—also inherited this fear reaction, as did mice born through in vitro fertilization using sperm donated from mice trained to fear acetophenone.
Although the researchers are not certain how this fear passes from one generation of mice to the next, they suspect it is due to a form of epigenetic modification. In epigenetics, the activity of certain genes—not the DNA sequence itself—is altered by a reversible chemical process, a change that may be passed onto offspring.
The researchers have yet to show how this works in mice, but other studies hint at the possibility of similar cross-generational changes in human. If it turns out to be true, then mental health problems caused by the environment might also be visited upon people’s children, and possibly even their grandchildren.
“To remain stable is to refrain from trying to separate yourself from a pain because you know that you cannot. Running away from fear is fear, fighting pain is pain, trying to be brave is being scared. If the mind is in pain, the mind is pain. The thinker has no other form than his thought. There is no escape.”
~ Alan Watts, The Wisdom of Insecurity
