Biological (Relationship between Genetics and Behavior) Studies

Question 1

Kendler

Answer 1

Aim:
- observe twins to determine the role genetics play in depression

Procedure:
- 42,000 twins from Swedish registry (15,500 pairs)
- did phone interviews using computerized diagnostic interview designed to measure lifetime prevalence of depression
- 8,000 met criteria for MDD or voluntarily said they were taking antidepressants
- looked for genes (monozygotic vs. dizygotic pairs), shared environments, individual environments, and generations (covered decades in study)

Results and Conclusions:
- overall heritability was 38%
- concordance rates higher for monozygotic, higher for female pairs
- little to no effect of shared environmental factors or historical time period of twins

Strengths and Limitations:
- correlational, no cause-and-effect determined
- no specific gene isolated and tested
- confirms previous research, reliable
- self-reported answers could lead to variability
- large and representative sample

Question 2

Wedekind

Answer 2

Aim:
- determine if one’s MHC (Major Histocompatibility Complex) would affect attractiveness and mate choice (more varied MHC genes results in stronger immune system)

Procedure:
- 49 females, 44 males
- had MHC analyzed prior
- men asked to wear a t-shirt for two nights in a row with no external fragrant products
- women smelled shirts, 3 from MHC similar men and 3 dissimilar and asked to rank on pleasantness, sexiness, and intensity

Results and Conclusions:
- women scored different MHC shirts as more pleasant
- reversed for those using contraceptives, possibly because bodies were mimicking pregnancy and therefore did not need to select a mate