Heritability of Intelligence

Question 1

Nature vs. Nurture Debate

Answer 1

• Sir Francis Galton initiated the study of intelligence heritability in the 1800s, exploring whether intelligence is inherited (nature) or shaped by the environment (nurture).
  
  • Galton introduced studies of eminent families and twin/adoption studies to explore genetic vs. environmental influences on intelligence.

Question 2

Genetic Heritability of Intelligence

Answer 2

• Heritability in intelligence research refers to the extent to which genetics accounts for differences in intelligence across populations.
  
  • Heritability is measured as h², representing the proportion of variance in intelligence attributed to genetic factors.

Question 3

Methods for Assessing Heritability

Answer 3

• Family Studies: Compare intelligence across family members who share varying degrees of genetic similarity.
  
  • Twin Studies: Use identical (MZ) and fraternal (DZ) twins to evaluate genetic influence, as MZ twins share 100% of genes and DZ twins share about 50%.
  • Adoption Studies: Contrast adopted children with their biological and adoptive families to assess environmental impact separate from genetics.

Question 4

Heritability Estimates

Answer 4

• Studies suggest an average heritability of intelligence around 50%, indicating that about half the variation in intelligence across a population may be genetic, though this is an approximation and varies with environmental context.

Question 5

Limitations and Evolving Understanding

Answer 5

Traditional models of heritability (additive assumption) oversimplify genetic and environmental interplay. Modern views acknowledge a more complex interaction.