Genetics and behavior is a crucial topic in psychology that explores how genetic makeup influences behavior and mental processes. This topic is particularly emphasized in the Higher Level (HL) International Baccalaureate (IB) Psychology syllabus. The study of genetics and behavior involves understanding the role of genes, genetic similarity, and evolutionary explanations in shaping behavior. This document will delve into these aspects, focusing on key studies and concepts to provide a comprehensive understanding.
Genes are the basic units of heredity found in all living organisms. They contain the information necessary to build and maintain cells and pass genetic traits to offspring. Each gene is a segment of DNA located at a specific point on a chromosome.
Note
Human beings have 23 pairs of chromosomes, and the human genome consists of approximately 25,000 genes.
While no single gene governs complex behaviors, certain genes have been linked to specific behavioral tendencies. For example, the MAOA gene has been associated with aggressive behavior.
Example
In real life, this study suggests that individuals with certain genetic predispositions may be more vulnerable to the effects of adverse environmental conditions.
Common Mistake
It is a common misconception that the MAOA gene alone determines aggressive behavior. Environmental factors also play a significant role.
Genetic similarity refers to the proportion of genes shared between individuals. Human beings are 99.9% genetically similar to each other.
Twin studies are instrumental in understanding the role of genetics in behavior. They compare monozygotic (MZ) twins, who share 100% of their DNA, with dizygotic (DZ) twins, who share 50% of their DNA.
Example
This study implies that if one identical twin has MDD, the other twin has a higher likelihood of developing the disorder compared to fraternal twins.
Evolutionary psychology examines how evolutionary processes, such as natural selection, shape behavior. Traits that enhance survival and reproduction are more likely to be passed on to future generations.
Tip
Understanding evolutionary psychology can provide insights into human behavior that are not immediately obvious from a purely environmental perspective.
Note
This study highlights the influence of evolutionary pressures on gender differences in sexual behavior.
Epigenetics involves changes in gene expression that do not alter the DNA sequence but can be passed on to offspring.
Aim: To investigate how maternal behavior in rats affects epigenetic changes in offspring.
Procedure:
Results: Pups raised by high LG-ABN mothers showed more significant differences in DNA methylation compared to those raised by low LG-ABN mothers.
Conclusion: Maternal behavior can induce epigenetic changes that affect offspring behavior.
Example
This study demonstrates how environmental factors, such as maternal care, can influence genetic expression and behavior in animals.
Topic Key Studies Genes & Behavior Brunner et al. (1993), Caspi et al. (2003) Genetic Similarity McGuffin et al. (1996) Evolutionary Explanations Buss et al. (1989), Clarke & Hatfield (1989) Genetics & Behavior in Animals Weaver et al. (2004)
The study of genetics and behavior in psychology provides valuable insights into how genetic factors influence behavior and interact with environmental factors. By examining key studies and understanding the underlying concepts, we can better appreciate the complexity of human behavior and the role of genetics in shaping it.