Behavioral genetics: definition, and its 5 most important findings

This science investigates how genes influence our behavior and personality.

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

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

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

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

Behavioral genetics, also known as behavioral genetics, is a scientific discipline that studies the influence of genetic makeup on behavior and the interaction between heredity and environment as they affect behavior. 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 much a matter of knowing whether genes are important or not, but rather of studying the extent to which they affect a specific behavior.

In this sense, behavioral genetics tries to answer questions such as: How do genes and environment interact to influence behavior? Which specific genes are responsible? What is their mechanism of action? The field of this discipline is advancing rapidly, as we have increasingly better technological means to observe and study in depth the genes involved in each behavior.

Historical background

Behavioral genetics, or at least the study of the relationship between behavior and genetics, has been the subject of interest of numerous researchers since the end of the 19th century.

It was the English polymath, Francis Galton (Charles Darwin's cousin), who pioneered twin research and 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, several publications based on twin and adoption studies brought to the table the importance of genetic factors in relation to IQ and some psychiatric pathologies such as schizophrenia. The controversy that arose 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 shifted from studying racial differences to focusing on the influence of genetic factors on individual differences based on constructs such as personality, cognitive abilities or psychopathology. By the 1980s, behavioral genetics had established itself as a fully-fledged scientific discipline, and the scientific community supported the importance of heredity in explaining levels of intelligence, as measured by an indicator such as IQ.

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

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

Methods of study

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

Research is conducted in both animals and humans; however, studies using animal models tend to provide more accurate data than research conducted in humans, since both the genes and the environment can be manipulated and controlled in the laboratory.

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

In twin studies, if monozygotic twins are significantly more similar than dizygotic twins, 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 should 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 at the same time. . Another method of study is adoption, in which a quasi-experimental design is performed based on the fact that adopted children are separated early from their Biological parents, making it possible to study the separate effects of nature and nurture. One of the most prominent studies was conducted in 1966 by geneticist Leonard Heston, showing that children adopted away from their schizophrenic biological mothers had the same chance of developing the disease (about 10%) as children raised by their biological mothers with schizophrenia.

Major scientific findings

Through the use of genetically sensitive designs, such as twin studies or adoption studies, behavioral genetics research has generated several scientific findings over the years.. The following are the main findings.

1. All psychological traits show significant genetic influence

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

2. No trait is 100% heritable

Although heritability estimates are significantly greater than 0%, are also significantly lower than 100%.. Heritability percentages are significant, generally between 30-50%, but far from 100%.

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

Scientific studies show that many genes affect complex traits, such as behavior.as is the case with behavior. If only a few genes were responsible for the heritability of a trait, the selected lines would separate after a few generations and would no longer diverge in the following generations.

4. The heritability of intelligence increases throughout development.

Numerous investigations have shown that the heritability of intelligence (consistently over more than three generations) increases over time. (consistently for more than three decades) increases linearly throughout life. A finding made in longitudinal and cross-sectional analyses, as well as in 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 disorders, it is genetics that is responsible for the similarity between siblings.

Although environmental effects may have an important influence, these do not trigger siblings growing up in the same family to be similar in their behavioral traits.

Bibliographical references:

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

• 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. A. (1984). Genética de la conducta. Alianza Editorial.