When people talk about 'pit bulls', there is often a lot of talk about genetics and whether certain types of dogs are genetically predisposed to certain traits that may make them more dangerous to the public. This inevitably leads to a nature vs nurture discussion. But the entire conversation may not even be that easy (and that one isn't easy).
Simply put, Epigenetics is based on scientific evidence that shows that nature may be a more powerful factor than we could have ever predicted. Not only can we be shaped by the environment that surrounds us, but historical evidence suggests that powerful environmental conditions can somehow leave an "imprint" on our genetic material that can then be transferred to future generations. Environmental factors like diet, stress and prenatal nutrition can not only affect how our genes are expressed, but can affect future generations as well.
In his upcoming book, "The Genius in All of Us: Why Everything You've been Told Abut Genetics, Talent and IQ Is Wrong", science writer David Shenk calls epigentics a "new paradigm" that "reveals how bankrupt the phrase 'nature vs nurture' really is."
At this point, it seems unlikely that epigenetics would change how we emotionally react to certain events, it may affect how we physically react (sweaty palms, higher heart rate, etc).
The science itself is pretty new -- and most of its applications have been focuses seemingly on cancer research -- so it would be mere speculation on what impact epigenetics really has on canines in one way or the other. However, one thing would seem pretty evident -- and that's the tremendous diversity that would exist within a particular breed of dog. Not only would dogs be a product of their genetics, and of their environment - -but also products of the specific environment of previous generations. It also seems to point at an increased need for officials to focus on animal abuse and cruelty for long-term public safety concerns.
It will be interesting to see how this new area of science evolves over time, but it seems all the more reason that we need to be treating dogs as individuals -- uniquely shaped by their own genes, environment, and the environment of their parents -- with their own specific attitudes and behaviors. It's not just an opinion...it's science.
You can read the Time Magazine article here-- it's easily the most readable information on the topic I've found for non-scientists.