The tale begins with a pregnant mouse in a laboratory in Boston, Massachusetts who, unfortunately for her, was kept on a near-starvation diet when she was close to giving birth. As scientists expected, her babies were born smaller than usual. When they were raised normally, they still later developed diabetes.
What the scientists didn’t expect however is that even though these new generation of mice were raised normally and well fed, when they themselves gave birth, their own young were also born unusually small and with a higher risk of diabetes.
This made no sense, because nothing had changed genetically in this third generation of mice and they hadn't suffered any problems in the womb or after they were born. By current science they should have been perfectly healthy.
In seeking to answer the eternal question of nature versus nurture – do our genes or our environment dictate who we become – this experiment has radically introduced a mysterious third element into the mix: the life experience of previous generations.
This mysterious third element is a relatively young branch of science called epigenetics.
Since the 1970s, researchers had already known that cells all started off identical and that the tightly wound spools of DNA inside each cell’s nucleus require something extra to tell them exactly which genes to transcribe, whether for a heart cell, a liver cell or a brain cell. What we now know is that it is the epigenetics of the cell carries this extra information.
More recently we are beginning to ask questions such as if diet and chemicals can cause epigenetic changes that are passed on through generations, could certain experiences — child neglect, drug abuse or other severe stresses — also set off epigenetic changes to the DNA inside the neurons of a person’s brain? That question turned out to be the basis of a new field, ‘behavioral epigenetics’, which has spawned dozens of studies and suggested profound new treatments to heal the brain.
Professor Marcus Pembrey, a geneticist at University College London and the University of Bristol says behavioural epigenetics means a change in our genetic activity without changing our genetic code. Chemical tags get attached to our genetic code, like bookmarks in the pages of a book, signalling to our bodies which genes to ignore and which to use.
For decades, we have thought of our offspring as blank slates. Now, epigeneticists are asking whether in fact our environment, from smoking and diet to pollution and war, can leave "epigenetic marks" on our DNA that could get passed on to subsequent generations. They call the phenomenon epigenetic inheritance.
They gave male lab mice electric shocks every time they were exposed to the smell of acetophenone, a chemical used in perfumes because of its sweet fragrance, such as cherries and orange blossom. The eventual result was that the mice shuddered at the mere scent of acetophenone.
Again the surprise was that their children feared the smell, too, even though they hadn't received any shocks.
So did their grandchildren.
The results suggest that the fear of the smell of acetophenone passes into the sperm of the mice through some kind of chemical process, leaving epigenetic marks that aren't erased in the womb. Some reporters have likened it to a "memory" being passed down the generations.
What we are also realising is that similar can happen with humans.
Helen Epstein, the American daughter of survivors of Auschwitz and Theresienstadt, began her book Children of the Holocaust, “For years it lay in an iron box buried so deep inside me that I was never sure just what it was,” which launched something of a children-of-survivors movement when it came out in 1979. “I knew I carried slippery, combustible things more secret than sex and more dangerous than any shadow or ghost.”
Mult generational trauma
Just as trauma can be passed from one generation to the next so if your grandmother experienced trauma at an early age and this was not healed and processed, this might have been passed down to your parents and then also to you through epigenetics. This can then impact your responses to life in the present and make you reast with more fear to situations that you might otherwise.
The good news is that along with these recent discoveries in the field of epigenetics, we have also taken great strides in the field of trauma recovery and have developed new methods to heal trauma and clear it from your system permanently.
Regarding the common belief that addictions are genetic and passed down, epigenetic markers may be involved, so that if your parents drank excessively you may be more likely to.
However, what people usually find is that the underlying cause of this addiction is the trauma itself that has been passed on and that once people clear and heal their unresolved emotional material, their addictions often drop away of their own accord.
Alternatively if your grandmother was adopted by nurturing parents, you might be enjoying the boost she received thanks to their love and support. The mechanisms of behavioral epigenetics underlie not only deficits and weaknesses but strengths and resiliencies, too.