Michael White in Pacific Standard (Photo: epsos/Flickr):
The idea that our DNA, rather than being an immutable fact of our biology, is actually responsive to changes in our health and our environment is what makes people so enthusiastic about epigenetics. According to a popular metaphor, our genes themselves may be written in ink, but they're marked up in pencil—which can be erased and re-done. By developing drugs or treatments that modify these pencil marks, so the thinking goes, we can escape the limits imposed by our genes, which can't be changed. Cancer, for example, is caused by genetic mutations that can't be undone, but it is also characterized by abnormal epigenetic marks, which can potentially be reversed. Researchers have struggled for years, with little success, to fix our genetic print by repairing mutations with gene therapy. But in some cases we may not need to repair mutations if we can re-work the epigenetic pencil marks instead.
If this idea is right, the impact could be tremendous, because researchers have found epigenetic changes associated with almost everything. Distinct patterns of epigenetic marks are found not only in cancer, but most other common diseases as well, including psychiatric ones like depression and addiction. Differences in epigenetic marks are being linked with differences in socioeconomic status, and one study found epigenetic changes in suicide victims who had suffered childhood abuse. Even more worrying is the idea (still largely speculative) that epigenetic marks can be passed on from one generation to the next, meaning that parents may pass on the effects of their poor health choices, diet, or social environment to their children.
The potentially broad impact of epigenetics has drawn the attention of social scientists, who are not usually worried about the details of molecular biology. A team of bioethicists has called epigenetics one of the most “legally and ethically significant cutting-edge subjects of scientific discovery” because “a large range of environmental, dietary, behavioral, and medical experiences can significantly affect the future development and health of an individual and their offspring.”
This sounds both liberating and terrifying at the same time: Our destinies are not fixed by our genes, and yet much of what we do and experience could have a profound effect on the biological make-up of ourselves and our children. But the hype has outrun the science.