Epigenetic research is a hot-button topic at the moment, generating a lot of attention in both scientific studies and the media. Epigenetics is the ability of genes to be influenced by our experiences, altering our genetic make-up in real time. By changing the chemical signals that course through your brain and body, you can actually turn genes on or off, a process that can then influence your future actions. Thus, in some ways, epigenetics can be thought of as the bridge between nature and nurture—your behavior and environment affecting your biology, and vice versa. [...]
[And it] appears that these epigenetic changes not only affect our own behaviors, but that they can also be passed down to future generations.
This phenomenon—“transgenerational epigenetic inheritance”—was demonstrated recently in a study published in Nature Neuroscience about the inheritance of certain smell memories in mice, which were passed down through at least two generations.
In the study, mice were trained to be afraid of acetophenone, a fruity smell that’s used in cherry, jasmine, honey-suckle and almond flavorings. The researchers paired this fragrance with a foot shock so that it soon became a warning signal to the mice, instilling fear and alerting them to an impending attack. The mice’s noses and brains also adapted accordingly, generating additional M71 neurons—cells receptive to this particular scent—so that they would be extra sensitive to the smell. So far, this is all basic Pavlovian conditioning and neural adaptation, nothing special yet.
However, the crazy part is that the offspring of these mice, who had never before been exposed to that smell, also showed increased fear and startle responses to the scent. This suggests that the learned association, connecting the smell with danger, was passed down from one generation to the next. And this second group’s offspring also showed heightened sensitivity to the odor. Thus, three generations of mice were affected by the conditioning, even though only one of them had actually experienced it.
Consider the possible implications for human psychology. For example, could the traumatic experiences of an ancestor adversely affect the psychological functioning of succeeding generations, purely as a matter of biological inheritance? We're still far from drawing such a conclusion, but it doesn't seem nearly as farfetched as it may have seemed to us 20 or even 10 years ago. Though if you read the comments at the Atlantic post, some people seem upset about even considering the possibility that these findings might apply to human beings.