One of the most debated questions, and with no hope of ever being resolved, is the question of what is more important to define us: on nature which we are given (we could simplify it by saying that our genetics are inherited from our parents) or environment around us and how are we raised (epigenetics, microbiome, etc.)? The Anglo-Saxons put it simply by saying ‘nature versus nurture’. Let’s think a case of cancer to see the complexity of this equation. There are tumors with a clear familial predisposition, such as some cases of breast cancer and ovarian cancer (associated with germline mutations in the BRCA1 and BRCA2 genes) or certain subgroups of tumors of the colon, stomach and uterus (Lynch syndrome associated with germline mutations in the MLH1 and MSH2 genes). But the risk of developing cancer in carriers ranges from 60% to 90%, roughly speaking. namely things we do in our daily life and various exhibitions modulate this innate probability. We can reason the opposite as well. Let’s take the case of lung cancerwhere there are no well-described hereditary syndromes in adults: here the external factor is key, tobacco is the external condition that causes it. But at the same timethere are defiant smokers who do not develop lung cancer (although other respiratory pathologies do), that is, we believe they have a genetic endowment that makes them more resistant to exposure to tobacco carcinogens. Balances and imbalances, seeking to understand what has a greater influence on the development of a disease, whether our internal predisposition or the environment that surrounds us.
Besides disease, we can study other patterns in human beings to understand the contribution of our nature versus our nurture or exposure. It’s just that the researcher has to look to those groups of people to find those answers. An example was our study in monozygotic twins (they come from the same “egg” or zygote, excuse me). These brothers have it right 100% identical genetic material. So if only “nature” mattered, they should be exactly the same, perfect photocopies. But we know that’s not the case. For example, one may be more obese and another thinner; one more sociable and one more shy; one develops pathology at an early age and the other does not… Well, years ago we discovered it these twins may have epigenetic differences, that is, in the chemical signals that control gene activity. And the more different the environment that surrounds each twin, the more epigenetically different they will be.
Another example is our recent one a study of people who have strikingly similar facesbut they are not family. When we started this work years ago, the initial hypothesis was this his environment have shaped their faces in a similar way, but the results show otherwise: these Virtual “twins” share a number of genetic variants which affect the shape of the nose, eyes, lips, bone structure and fat distribution, among other parameters. We believe that these matches at these positions of their DNA sequence are due to random, in part increasingly likely as the number of people inhabiting this beautiful planet increases. Interestingly, perhaps the differences between these individuals are due to other biological “layers,” such as the aforementioned epigenetic marks and the composition of microbes in these individuals. And apparently there is a graduation similar to 90%, 85%, 80%… There are already many virtual applications that teenagers and young adults use to find their “double”.
Note that these studies have a lot to do with a concept I’m particularly interested in, like that of identity. The tumor cell has lost its identity and we do not recognize it. Twins have their own identity even though they share the same genome. In the quadrilateral we find determinism versus the ability to change. Nature vs. nurture and environment. There is no clear winner in this eternal boxing match.