Epigenetics is the study of environmental effects, including lifestyle habits, on an organism’s underlying genomic material or DNA. The underlying epigenetic mechanisms, are modifications to the DNA that dictate whether a certain gene will be turned on or off, carrying its own consequences on health and development.
Many diseases such as cancer, diabetes, obesity and several mental disorders are genetic in nature, meaning a person is at more risk of developing a certain disease if he/she carries a gene or set of genes shown to be involved in driving disease onset. However, this is not always the case. Many individuals end up developing a certain disease with no signs of carrying the “bad” genes. That was when scientists started to wonder whether those disease may also hold an epigenetic influence, that is passed on from one generation to the next. For example, are the environmental exposures (such as the use of recreational drugs) inducing epigenetic changes to an individual (‘s brain) carried across generations, making the subsequent generations more susceptible to particular (mental health) diseases? That was the initiation of a subfield within epigenetics, known nowadays as: Transgenerational Epigenetics.
Every single cell- the building block of an organism- in the human body, carries the same DNA. However, what makes a neuron so different from a heart cell, are the distinct epigenetic patterns of those cells. While genes X, Y and Z are turned on in neurons, the same genes might be completely inactive in heart cells. And these epigenetic changes persist during cell division, so that a newly born neuron grows into being a neuron and not a heart cell. But what is typical about epigenetic switches is that they constantly change throughout development, and especially in response to external environmental and lifestyle factors, such as exposure to toxins, diet, physical activity, psychological state, socio-economic status among many more, switching genes on or off. For instance, if a pregnant woman smokes, there will be changes to which genes will be active or not in the baby (this is epigenetics). If then the person grows up and also smokes, they will also cause changes to their genes. So even though the genes across one’s life are the same, the epigenetics are not necessarily the same, they change depending on your lifestyle.
Research recently published, has proposed that epigenetic information can be passed on from one generation to the next. For instance, a study lead by Isabelle Mansuy, PhD at the University of Zurich, has shown that the effects on laboratory animals exposed to traumatic stress can be passed over to next generations, even when these generations have not been exposed themselves to a similar traumatic event. Another human study, in support of the animal study has shown that the traumatic effects of Holocaust survivors were transmitted onto their children. However, while those suggest involuntary exposures to such circumstances and events, what about those that are voluntary? A grandmother who spent her young adulthood consuming recreational drugs, altering her own epigenome, might hypothetically transmit the harmful epigenetic patterns of her habit to her subsequent generations. For instance, a research study has shown that smoking upregulates certain hormones involved in appetite, which if carries transgenerational effects, might lead to increased risk of obesity in subsequent generations. That being said, when a “non-contagious” disease becomes “contagious" to the coming generations, should we be held accountable of our habits?
Skeptics might cut this long story short and state that transgenerational effects are not robust claims. And this might be true, the field of epigenetic is still in its infancy and the methods used to measure epigenetic modifications carry several limitations. Additionally, several generations need to be tested before such claims can be made, which is a time consuming process. However the science is there, the technologies are improving by the minute and the current research carries some important findings that we cannot just choose to look away from. Maybe at this point in time, before making a priori conclusions and while we wait for more scientific evidence, we should attempt to be more responsible, more epigenetically proactive (Google it). Not considered a problem today doesn’t imply not a problem tomorrow! Changing our lifestyle habits will not only benefit us but our daughters/sons, our granddaughters/grandsons.
Katherine C. Bassil