Examining Nature and Nurture Interplay

Sep 1, 2024

Lecture Notes: Nature vs. Nurture and Heritability

Introduction

  • Nature vs. Nurture Debate
    • Historical debate: John Locke (environment), Charles Darwin (genetics)
    • Modern view: Interaction between genetics and environment
    • Example of a 7-year-old girl with a poor report card

Understanding Genetics and Environment

  • Genes and Environment
    • Genes: Influences before conception
    • Environment: Influences after conception
  • Complexity of Influences
    • Siblings experience different environments
    • No single gene affects a single trait

Heritability

  • Definition
    • Heritability ranges from 0 to 1
    • 1 = Genetic influence; 0 = Environmental influence
    • Measures genetic impact on trait differences in a population
  • Examples
    • Dyslexia has high heritability (closer to 1)
    • Does not determine individual traits genetically

Height and IQ as Case Studies

  • Height
    • Group example: Average height of 178 cm (5'10")
    • Heritability for height is about 0.8
    • Environmental factors can affect heritability (e.g., nutrition)
  • Intelligence (IQ)
    • Heritability of IQ is around 0.6 in twenties, increases with age
    • Average IQ = 100, variation due to both genetics and environment
    • Random factors play a significant role

Random Environmental Factors

  • Sibling Example
    • Firstborns often more intelligent
    • Adopted siblings show similar IQ in childhood, but not adulthood
  • Limited Parental Impact on IQ

Crayfish Experiment

  • 1995 Experiment in Germany
    • Asexual crayfish: Identical genetic clones
    • Outcomes varied despite controlled environments
    • Indicates complexity beyond nature and nurture

Conclusion

  • Complex Interactions
    • Genetic and environmental influences are complex, with randomness
    • Crayfish study challenges simple nature/nurture explanations

Additional Resources

  • SproutsSchools.com
    • Creative Commons license for educational use
    • Support and further information available through Patreon

This lecture covered the complex interplay between genetics and environmental influences, using examples from human and animal studies to illustrate the nuanced nature of heritability and trait formation.