Genetics, Evolution, and Personality: Foundations and Influences

Genetics, Evolution, and Personality

Learning Objectives

• Describe the procedures of twin studies and adoption studies.

• Identify estimates of the personality qualities that are genetically influenced.

• Summarize outcomes in behavioral genetics research on nonshared versus shared environments.

• Describe the processes of natural selection and sexual selection.

• Examine four ways in which psychologists have applied the logic of evolutionary theory to personality.

• Summarize how temperament fits the genetic and evolutionary perspectives on personality.

• Review ways in which researchers have studied the heritability of subjective well-being.

• Describe how evolutionary understanding contributes to the study of individual differences.

6.1 Determining Genetic Influence on Personality

Introduction to Behavioral Genetics

Behavioral genetics is the field that studies the influence of genetic and environmental factors on behaviors and traits, including personality. Researchers use various methods to estimate the heritability of personality traits and to distinguish between genetic and environmental contributions.

• Twin Studies: Compare similarities between identical (monozygotic) and fraternal (dizygotic) twins to estimate genetic influence.

• Adoption Studies: Examine similarities between adopted children and their biological versus adoptive parents to separate genetic and environmental effects.

Heritability refers to the proportion of observed variation in a trait among individuals that can be attributed to genetic factors.

• Example: If identical twins raised apart are more similar in personality than fraternal twins raised together, this suggests a strong genetic component.

Additional info: Heritability estimates for major personality traits (such as the Big Five) typically range from 40% to 60%.