Which research methods are most often used to study genetic influences on behaviour in the Biological approach?

• A. Twin and family studies
• B. Case studies
• C. Ethnographic observation
• D. Self-report surveys

Answer: (A)

Genetic influences on behaviour are best investigated with designs that compare related individuals to separate inherited factors from the environment. Twin and family studies do this by using different levels of genetic relatedness. If a trait is influenced by genes, identical twins, who share nearly all their genes, will be more similar on that trait than fraternal twins, who share about half. This difference in similarity helps researchers estimate how much of the variation in behaviour is due to genetics (heritability). Family studies extend this by looking at other relatives to see how similarity declines with decreasing genetic relatedness, reinforcing the genetic link.

Other methods here don’t directly quantify genetic influence. Case studies look in-depth at individuals without disentangling genetic from environmental effects in a generalizable way. Ethnographic observation focuses on social and cultural contexts rather than genetic contributions. Self-report surveys collect subjective data and can’t cleanly separate inherited factors from experiences.