Behavioral genetics, basics

Behavioral genetics, basics

DNA and behavior

Behavioral genetics or Psychogenetics is the study of the influence of the genetic composition of an organism in relation to its behavior and the interaction of inheritance and the environment to the extent that they affect behavior.


  • 1 The inheritance and the environment
  • 2 What studies behavioral genetics
  • 3 What is a gene?
  • 4 What is a chromosome?
  • 5 The common origin of the species
  • 6 The interaction between genes, the environment and the environment

The inheritance and the environment

All studies to date on behavioral genetics have shown that almost all personality traits have biological and environmental bases.

Environmental influences can be divided into two classes, the shared environment and the non-shared (or single) environment. The shared environment It is the environment shared by brothers raised in the same family. This includes variables such as socioeconomic status and parental education. The non-shared environment It is the exclusive environment of the individual. This includes variables such as group of friends, coworkers, etc.

It is important to keep in mind that there is no single gene for personality, intelligence, behavior or even height. On the contrary, such characteristics are complex and polygenic, that is, they are influenced by multiple genes.

The recognition of the importance of genetic factors in behavior, and specifically in certain psychopathologies and neuronal diseases that affect behavior, is one of the important facts that has been recognized in recent decades.

What does behavioral genetics study?

The behavioral genetics studies the genetic and environmental influences that give rise to differences in behavior; In short, knowledge of the genetic basis (and environmental influences) of normal behavior and psychopathology, as well as the psychological disorders associated with genetic alterations, be they gene or chromosomal.

Diseases that have a genetic basis have a great impact on health, because although the frequency of some of these is very low, the total incidence of genetic alterations in health is important, especially in Western societies, where death For environmental reasons (malnutrition, infections, etc.) it has been greatly reduced. The participation of inheritance in diseases and deaths, especially children, has increased significantly in the last hundred years.

What is a gene?

The genes are fragments of the DNA molecule that contain the instructions for building proteins Essential for life. Genes represent only 3% of DNA. The DNA of all living things has the same structure, which allows, for example, the exchange of genes between different species.

Cell division

Human beings have 22 pairs of identical chromosomes to which we must add the pair of sex chromosomes called XX in women and XY in men.

Before the cell divides all the chromosomes duplicate in the nucleus, so that each of the two resulting cells possess an identical set of chromosomes. In this way, the total genetic information of the original cell is transmitted to each daughter cell.

After duplicating the DNA, Each chromosome is composed of 2 identical strands of DNA, although the chromatids in the beginning still remain united in the center. Subsequently, the nuclear membrane dissolves and the chromosomes are arranged in their plane.

In each of the cell poles a new nuclear membrane forms around the chromosomes. Thus, two new nuclei with the same number of chromosomes are formed. Subsequently, the chromosomes lengthen again.

That is when the rest of the cell is also divided. The result is two new cells, each with identical genetic material..

What is a chromosome?

Chromosomes are the basic components of life and it is in where the entire genome of an organism is stored in the form of DNA (deoxyribonucleic acid). A chromosome is a unique strand of DNA that coils and coils super to form dense pieces similar to threads. The term chromosome is derived from the Greek words "chroma" or color and "soma" or body and is so named because chromosomes have the ability to dye with dyes.

The extended DNA of a cell measures almost two meters, while the cell nucleus that contains it has a diameter of one hundredth of a millimeter. Entering the DNA in the nucleus is like putting two kilometers of thread the thickness of a hair inside a hazelnut. Chromosomes save space in the cell nucleus. They are composed of protein discs on which DNA is rolled as if they were curlers, a compact folding system that saves a lot of space.

Alterations in the process of duplication of genetic information

Unfortunately it is estimated that 1% of newborns express some genetic alteration. Another 1% manifest a serious genetic alteration a few years after birth. The global estimate is that 10% of admissions in pediatric hospitals are due to genetic causes.

Many of these genetic alterations have a very clear effect on the behavior and / or intellectual abilities of the affected people., and every day the participation of the genetic substrate in many of the psychopathologies is more evident.

The common origin of the species

There are many data that suggest that development from the embryo to the adult organism follows the same basic principles throughout the animal kingdom. When comparing the embryos of a human being, a rabbit, a bird or a fish, one can hardly predict whether the upper extremities will become an arm, a leg, a wing or a fin.

A human being and a mouse barely distinguish themselves in the early stages of their development. The differences do not arise until later, because the parts of the body that develop earlier are closest to the trunk. The genes responsible for this development are virtually identical in all animals. Only when the genes that determine the subsequent development act will it be known if that lump will become an arm or a fin.

The interaction between genes, the environment and the environment

The genetic information stored in the genes only determines the initial conditions for the development of the organism.

The final appearance of a living being is the result of the interaction between its genes and cells through the signals and compounds that act as messengers. Environmental factors such as nutrition, duration of the day and temperature are also involved in the final result.

This also happens with some mental illnesses such as schizophrenia, the Bipolar disorder wave major depression, which have a predisposition or genetic susceptibility. But this factor is not enough to explain the development of these pathologies, for the disease to develop it must interact with certain environmental triggers.

In summary, while it is true that there are people with a higher genetic risk to develop a psychiatric illness, it is also true that they have compensatory environmental mechanisms that can avoid it.