Epigenetics and the Holocaust
I just saw an interesting video on epigenetics. Research is revealing that much of what makes us biologically unique as a species, and as individuals, is not just determined by our genomes. Human beings have a relatively small number of genes (about 20,000, far less than some plants), and most of our genes are identical to that of other organisms (99% of our genome, for example, is the same as a chimpanzee’s). Even identical twins, with the exact same genome, can have widely divergent medical histories. One can be bright and productive, for example, and the other autistic. So clearly much of what makes us unique is not the genes themselves, but our epigenetics: the patterns of which genes are turned on (expressed) or not. There are two interesting facts about this. One is that a person’s epigenetics is impacted by their history. Gene expression is governed among other things by the chemical markets (e.g. methyl groups) attached to our genes or to the histones around which those genes are wrapped. Some kinds of experiences (e.g. smoking, drinking, and starvation) can change our patterns of epigenetic markers in a way that is very persistent over time. The second interesting fact is that epigenetic markers can be inherited. Someone whose grandfather experienced a famine as a boy, for example, will be far less prone to diabetes than one whose grandfather did not, even though the child did not experience the famine him or herself. These two facts imply a previously unsuspected, cell-level mechanism for the impact of experience across generations. My parents are Holocaust survivors and, in all likelihood, had their epigenetics deeply impacted by that experience. In a very real sense, therefore, the Holocaust was imprinted into every one of my cells, at birth, and the same is true for Hannah, my daughter. Our experiences can thus ricochet through the generations at a deep biological level: a sobering thought for a parent.