Behavioral genetics: definition, and its 5 most important findings

Behavioral genetics is a science that studies how our genes influence behavior and in the development of our psychological and behavioral traits.

Through comparative studies with twins and adopted children, experts in this scientific field have They strive to understand the genetic mechanisms involved in behavior and in various diseases.

In this article we explain what behavioral genetics is and what it studies, what are its historical background, its study methods and the main findings arising from this discipline scientific

Behavioral genetics: what is it and what does it study?

Behavioral genetics, also called behavioral genetics, is a scientific discipline that is responsible for studying the influence of genetic composition on behavior and the interaction between inheritance and the environment as they affect behavior.

Today we know that the vast majority of behaviors studied in psychology are affected by the particular genetics of the individual in question, so it is not so important to know if genes are important or not, but rather to study to what extent they affect behavior specific.

In this sense, behavioral genetics tries to answer questions such as: How do genes and the environment interact to influence behaviors? What specific genes are responsible? What is your mecanism of action? The field of this discipline is advancing rapidly, since every time we have better technological means to observe and study in depth the genes that intervene in each behavior.

Historical background

Behavioral genetics, or at least the study of the relationship between behavior and genetics, has been the object of interest of many researchers since the late 19th century.

He was the English polymath, Francis Galton (Cousin of Charles Darwin), the pioneer in twin research and in the use of many of the statistical methods of analysis currently in use. This scientist carried out the first systematic studies with families, demonstrating how certain behavioral traits could be transmitted and inherited from parents to children.

In the 1960s, various publications based on studies of twins and adoption brought to the table the importance of genetic factors in relation to the intelligence quotient and some psychiatric pathologies such as schizophrenia. The controversy arising from the articles published by the psychologist Arthur Jensen, who suggested that differences in intelligence were mediated by race, also served as a spur for behavioral genetics to continue to develop as a discipline.

After the most controversial years, the discipline went from studying racial differences to focusing on the influence of factors genetic differences in individual differences based on constructs such as personality, cognitive abilities or psychopathology. As early as the 1980s, behavioral genetics was established as a full-blown scientific discipline, and the scientific community supported the importance of heredity in explaining levels of intelligence, measured with an indicator such as IQ.

Currently, scientific research related to behavioral genetics is increasingly abundant, thanks to the work of a multitude of scientists coordinated in projects such as the Genome Project Human, in which the sequence of chemical base pairs that make up the DNA and about 25,000 genes of the human genome were identified.

Robert Plomin, one of the leading geneticists, has suggested that the responsible genes will be identified in the coming years. of the heritability of behavior and we can begin to trace the routes that go from genes to the brain, and from the brain to the conduct. Furthermore, the scientist insists that behavioral genetics is the scientific discipline that best interprets the importance of the environment when explaining individual differences.

Study methods

In behavioral genetics, quantitative genetic methods are used to estimate the net effect of genetic and environmental factors on individual differences. on any complex trait, including behavioral traits. In addition, molecular genetic methods are used to identify the specific genes that are responsible for a certain genetic influence.

The research is carried out in both animals and humans; However, studies using animal models tend to provide more accurate data than research conducted in humans, as both genes and the environment can be manipulated and controlled in laboratory.

Due to the impossibility of manipulating genes and the environment in human research, two are usually used quasi-experimental methods to detect genetic influence on individual differences in traits behavioral; the twin method, based on the comparison of monozygotic twins (they are genetically identical to each other and come from the same egg) and dizygotic (developed from two fertilized eggs at the same time).

In twin studies, if they are monozygotic they are significantly more similar than dizygotic, it means that genes play a determining role in the behavioral trait; that is, to the extent that behavioral variability is caused by environmental factors, dizygotic twins must be as similar for the trait in question as monozygotic twins, since both types of twins are raised by the same parents in the same place and at the same weather.. Another study method is adoption, in which a quasi-experimental design is carried out based on the fact that the adopted children are separated early from their biological parents, making it possible to study the separate effects of nature and breeding. One of the most prominent studies was carried out in 1966 by the geneticist Leonard Heston, showing that children adopted far from their schizophrenic biological mothers had the same chance of developing the disease (about 10%) than children raised by their mothers biological with schizophrenia.

Main scientific findings

By using genetically sensitive designs, such as twin studies or adoption studies, research in behavioral genetics has generated diverse scientific findings over the years. The main findings are listed below.

1. All psychological traits show significant genetic influence

Psychological traits have consistently shown a significant genetic influence in studies, which has led to the description of the first "law" of behavioral genetics.

2. There is no 100% heritable trait

Although the heritability estimates are significantly greater than 0%, are also significantly less than 100%. The percentages of heritability are important, generally between 30-50%, but very far from 100%.

3. Heritability is caused by the small effect of many genes

Scientific studies show that many genes affect complex traits, as with behavior. If only a few genes were responsible for the heritability of a trait, the lines selected would separate after a few generations and would not diverge further in subsequent generations.

4. The heritability of intelligence increases throughout development

In numerous investigations it has been proven that the heritability of intelligence (consistently over three decades) increases linearly throughout life. A finding made in longitudinal and cross-sectional analyzes, as well as adoption and twin studies.

5. Most environmental effects are not shared by children growing up in the same family

Although, a priori, it might seem that growing up in the same family makes siblings psychologically similar, the truth is that in most dimensions of behavior and in the development of psychological disordersIt is genetics that is responsible for the similarity between siblings.

Although environmental effects can have an important influence, they do not cause siblings who grow up in the same family to be similar in their behavioral traits.

Bibliographic references:

• Gomez, P. (1995). The genetic determination of human behavior. A critical review from the philosophy and genetics of behavior.

• Plomin, R. 1990. Nature and nurture. An introduction to human behavioral genetics. Pacific Grove, California, Brooks / Cole Publishing Company

• Plomin, R., DeFries, J. C., McClearn, G. E., Pezzi, L., & Flores, E. TO. (1984). Genetics of behavior. Editorial Alliance.