2023-11-20 10:40:17
The Darwinian laws of evolution were slow to penetrate minds; conversely, genetics enjoyed rapid success. The expression “it’s in his DNA” is enough to sum up the enthusiasm of the media and the general public for determinism through genes.
However, if DNA is responsible for biological and morphological traits, it intervenes less on our behavioral traits. Advances in epigenetics confirm the primacy of the environment over behavior.
Epigenetic markings must be distinguished depending on whether they operate on somatic or germ cells. In the first case, they obviously have no repercussions on the next generation. Conversely, when germ cells are marked, intergenerational transmission is possible. However, most of these germline marks are erased before, during or just after fertilization, leaving the embryo with “cleaned” DNA from both parents. Then, life in uteroeducation and the environment will place new epigenetic marks on this DNA.
Freud and Lamarck ignored genetics and epigenetics. Freud rightly assumed that marks placed on the DNA of brain cells have repercussions on mood and behavior. As for Lamarck, if he was wrong about somatic markings, he was right about certain germinal markings.
Today, we have ample evidence of germline marks that are not reprogrammed, and therefore heritable. Some concern diet, the marks on sperm and eggs can be transmitted to offspring. The best-known example is that of the Dutch famine, the scars of which are experienced by the following generation.
We also know that exposure to drugs such as distilbene or pesticides have marked germ cells over more than two generations. The stress experienced by parents marks their brain cells, but can also mark their germ cells. For example, Holocaust survivors transmitted epigenes from the trauma they experienced to their children.
In the case of stress or nutrition, it is easy to understand that education can add other marks which will modify the expression of genes already marked by inheritance. Thus, obesity and anxiety can be both inherited and modulated or worsened by education.
Intergenerational epigenetic inheritance is defined as inheritance that crosses only one or two generations, while transgenerational is that which crosses several. We have ample evidence of transgenerational epigenetic inheritance in plants, but still very little in humans.
So, despite the great environmental disruptions we experience, it seems that the reprogramming of our germline still works quite well to eliminate the most deleterious epigenetic marks.
Hope it lasts…
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#Heritable #epigenes #health #reasons