The idea that social relationships can be dictated to a greater or lesser extent by people's genetic characteristics is relatively new. Sociogenomics - a scientific field that studies how various social factors affect the activity of the genome - emerged only in the early 2000s.
However, even in a relatively short period of time, scientists have found some evidence that people's DNA can adapt to the conditions of the social environment (eg, conflict, isolation, attachment, etc.). One of the first studies in this field was to examine how the genes responsible for immunity functioned in American retirees (the average age of the respondents was 55 years) depending on their level of loneliness. The results did not disappoint the scientists: they noticed a connection between the subjective feeling of social isolation and the expression of some anti-inflammatory genes.
Since then, the scope of the phenomena with which sociogenomics deals has greatly expanded. One such new topic is friendship.
Friends can bond on a genetic level
At first glance, it may seem that friendship is a purely social phenomenon. It is generally believed that people choose their partners based on shared moral values, level of education, interests, etc. However, this is only half the truth.
American research proves that friends are very similar genetically. The degree to which the DNA strands of people who communicate well correspond to the degree of genetic relatedness between fifth cousins. Scientists examined the genetic material of 2,000 people (1.5 million markers of gene variation) and found that the genetic relationship between friends is the same as that between distant relatives. Most often, the friends matched the genes responsible for the sense of smell.
Specialists explain the interesting data with the fact that genetic kinship between friends has provided humans with an evolutionary advantage. For example, when humans were just beginning to develop their speech centers, it was important to have another member of the species with a similar mutation. Otherwise, it would be useless and would not lead to the formation of a verbal culture of communication among people, because there would simply be no one to talk to. This hypothesis is also confirmed by another observation of scientists: common genes of friends develop faster than others.
Swedish research shows that the DNA of the people you hang out with as a teenager can affect your risk of developing alcohol and drug addiction, as well as depression and anxiety. As the authors of the paper explain, the genetic predisposition of a person's peers to certain types of addictions and disorders also affects how prone a person will be to such problems.
The experts analyzed data from more than 1.5 million respondents born in Sweden between 1980 and 1998. They looked at which areas of the country the schools they attended as teenagers were located in, and then requested information from medical records to find out whether whether the study participants had taken illegal substances and whether they had suffered from mental disorders in the future (between the ages of 17 and 30).
By comparing the data, the scientists realized how much the genetic characteristics of their classmates, which can lead to addictions or mental problems, influence the likelihood that the school community will face such problems in adulthood. And to make the results as objective as possible, the researchers also took into account the genetic characteristics of the participants themselves (how much such risks are present in their family history), as well as socioeconomic risk factors that can lead to such problems.
Moreover, the strongest effect is seen among peers who are classmates, rather than among teenagers who simply live in the same neighborhood. High school students, especially those who studied together from 16 to 19 years of age, had the strongest effect on each other (the effect was weaker in the 7-16-year-old group), especially on the development of addiction from harmful substances.
In a 2018 US study of 5,000 teenagers who went to school together in 1994-1995, scientists suggested that people's genetic identity is linked to homophily - people's tendency to socialize and bond with those who they look like them. And although classical notions of homophily do not go beyond socio-economic factors (age, gender, level of education, etc.), from the point of view of sociogenomics it is worth including genetics in the circle of formative components.
Another possible reason is the so-called social structuring. This phenomenon is based on the idea that people are attracted to those who are in the same social environment as them, which can already be formed under the influence of genetic factors. In other words, friends have more DNA in common because certain areas attract genetically similar people. Thus, at the university, people with a similar genotype find themselves in the art department, and people with a different genotype - in the school of Olympic reserves. As a result, people form close friendships with those who are genetically similar to them. | BGNES
