the part of variability linked to the environment can no longer be denied

Ihe enthusiasm for the Human Genome Project and the enormous amount of funding for it have prompted outlandish promises about its public health impact. In 2000, Francis Collins, director of the NIH [le financeur public de la recherche en médecine et santé aux Etats-Unis]predicted that the decoding of the human genome would allow a revolution in medicine in terms of prevention and treatment.

The contribution is undeniable for monogenic diseases (due to a rare DNA variant). But we are far from these promises for diseases, multifactorial, which result from complex processes involving genetic and environmental factors: endocrine, neurological, psychiatric diseases, etc.

At the same time, an Australian scientific team proposed using the correlations between genetic markers and complex diseases in order to calculate the risk for an individual of developing a multifactorial disease by ignoring environmental factors. It becomes possible, by simple reading of DNA, to separate what is genetic from what is environmental. The approach applied to samples from millions of individuals (including DNA collected by the company 23andMe, which sells genetic tests online) has given rise to exponential growth in publications in renowned scientific journals.

These same journals are now concerned about the societal impact of genomics, even though they have helped to give credibility to an approach that is incompatible with biological knowledge. Thus, to postulate the absence of interactions between genes and environment, is to deny the processes of regulation and reaction to the environment which occur throughout our life, from the fetal stage and even before (effect on embryo of the diet of the mother or of recent ancestors, of their exposure to toxic substances: tobacco, alcohol, pollutants, bacteria, viruses, etc.).

Non-genetic inheritance

In the same way, to postulate that genetic factors are transmitted independently of the environment is to deny the transmission of factors not encoded by parental DNA, which are grouped under the term non-genetic heredity. However, in addition to the transmission of socio-cultural factors, we have known since the 1990s that the effect of environmental factors can be transmitted over several generations.

It is therefore on the basis of erroneous umptions that we are witnessing a resurgence of the concept of heritability aimed at quantifying the share of genetic variability and environmental variability. However, since the work of geneticists like Albert Jacquard, in France, or Marcus Feldman and Richard Lewontin, in the United States, we knew these postulates were inapplicable in evolutionary biology and human genetics.

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