By Hugo Aguilaniu
Can a stepson "inherit" characteristics of his stepfather?
Over the past few decades the number of divorces has increased, as well as the number of family rearrangements. Nowadays it is common to grow up with a stepfather or stepmother, although Justice sometimes resisted equating them to biological parents (although less and less). In the eyes of society, the genetic link prevails over the affective bond. Implicitly, we consider that coexistence and genetics are distinct elements. But is this separation real? Can family life have genetic consequences?
As frightening as it may seem, DNA is considered an indelible, definitive and impossible to be counterfeited mark. It is a formidable tool to define our affiliations and legitimacy. However, now this genetic absolutism is being challenged by our understanding of an area known as epigenetics, which studies the changes in the functioning of a gene caused by environmental, external factors.
In each of our cells there are 46 DNA molecules organized into 23 pairs. They are found in the nucleus of the cell, which represents only 10% of its volume. Each of these molecules is linear and has units (called genes) capable of producing an effect on the cell. Sort of like a musical score with notes that would produce a sound. The proper functioning of the body then consists of playing, at the same time, 46 scores in each of our ten trillion cells.
In the case of the human being, our music has about twenty thousand notes distributed among 46 scores – twenty thousand genes in 46 linear molecules that are, consequently, very long. It is estimated that, in each of our cells, the DNA molecules in a row measure almost two meters.
When geneticists understood the importance of these notes and their order, they came up with an apparently trivial question: how is it possible to have two meters of DNA inside the tiny nucleus of a cell (about says cubic micrometers)? It is obvious that these strands of DNA need to be folded and compacted very carefully to fit in such a small space. The way these folds occur has become the object of study in epigenetics – not because scientists had a special interest in storage and compaction, but because it affects us enormously and in a fascinating way, for some reasons.
First, this organization largely determines the strength with which our genes will be expressed. It is as if these folds were the rhythm of our score. Depending on the chosen rhythm, we can ignore some notes, while others will be more prominent.
In addition, external factors such as climate, nutrition, pollution, etc. can have a direct impact on those folds. In other words, living conditions need to be taken into account. It is very likely, therefore, that members of a family, rearranged or not, have the same epigenetic regulations (in part), even though they do not share the same genes. Although your grades are slightly different, the pace will be identical.
It is extraordinary how these changes in the organization – in rhythm – are perpetuated throughout life and are sometimes passed on from generation to generation, just like genes. An example of this are the Dutch who starved and suffered from malnutrition during World War II. The descendants inherited epigenetic marks and, to this day, their grandchildren and great-grandchildren have a higher incidence of metabolic diseases such as diabetes.
This means that our genetic expression, which defines us biologically, is determined both by the notes on our score (the genes) that come with us from our biological parents, and by the rhythm of that score (the external factors) that we share with people with disabilities. who we live. Both the notes and the pace at which we play them can be transmitted to our children. It would then be plausible, from a biological point of view, that my stepson's future children will one day look a little like me.
Hugo Aguilaniu is a geneticist biologist and CEO of Instituto Serrapilheira.
sign up in the Serrapilheira newsletter to follow the updates of the blog Ciência Fundamental.