Epigenetics is natures equivalent to the invention of the wheel. Everybody knows about DNA; long threads on which the genes are lined up, the totality of which is our very own individual existence. To make the DNA more compact it is organized in different chromosomes like a thread being rolled up around a spindle. When the cell multiplies the whole DNA gets duplicated from one end to the other, a bit like duplicating an opening in a zip, and in the end there are two cells with identical DNA and chromosomes.
This model of genetics is very basic, like if you look for a recipe, you always would have to read the whole library. No spontaneous invitation there! Fortunately, genetics has categories, volumes, a list of content and an index list, in short it has epigenetics.
This is naturally more complicated. Starting with the first cells of an fertilized egg to be told what they are going to be and that they are going to stay like that, not to reverse into the first omnipotent cell again. If those cells, e.g a muscle cell, divide, they still carry a copy of the whole library within it, but epigenetics ensures that the cell is only reading the books about muscles. But epigenetics also communicates with the environment, not in terms of adding or losing DNA, but in a way that the environment influences whether a gene works according to plan A or plan B, i.e. it determines the sex in some insects.
How does all this work? I won’t and can’t be exhaustive, but the spindle or helix that I mentioned is not only one, but a few. It then depends on whether the beginning of the thread starts at its correct position to roll round the spindles and whether the thread is rolled up loosely or tightly in its orderly fashion. Tight loops, which should be loose, may not be read by the cell or the cell may not be able to read loose loops correctly, because occasionally they may be stuck together where they shouldn’t be. You see, despite index lists, it is difficult again to find the recipe.
I became fascinated about the interaction of the genes with the environment, during a report about embryos developing in the womb of pregnant Dutch women during the hunger winter of 1944-1945. The hunger of their mothers has caused a lifelong change of plan in the health of the now-pensioners, by making their bodies read some of the unchanged genes differently. Epigenetic changes also only can last until the next cell division, or even be passed on to the next (not yet conceived) generation as it is postulated for some cancers and Thalidomide victims.
People conceived during the famine still show on genes today differences how the loops are being read in comparison to normal and it is postulated, that the higher than expected incidence of obesity and heart disease, are due to those changes. Participants whose pregnancy was advanced during this time were underweight at birth, but did not show those changes. It is also known that some medicines alter the reading of some of our genes and some of the side effects may have the same mechanism.
And last but not least, (here my supermarket aversion shows again) hunger is malnutrition and this means ‘poorly nourished.’ What about all the chemicals that we ingest with modern food? Nobody knows. In rodents it already has been shown that plastic components mimicking oestrogen, ingested in early pregnancy, produce disability over generations without altering the gene sequence and special soja supplements produced a white fur. Frightening, our building plan is identical.