Twin Studies


"Sources of human psychological differences: the Minnesota Study of Twins Reared Apart" by Bouchard, Lykken, McGue, Segal, and Tellegen.

Hypothesis:  Genetics affects personality, which affects environment.

Sample size: 100 sets of reared apart twins or triplets

Summary of findings:  While genetics appears to have the largest affect on people's psychological traits/personality, parenting, education, and other environmental factors can have important effects.  For example, 70% of intelligence comes from genetics.

**What do you think...?  (Only answer one of the final two questions.)

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"Genetic Correlates of Musical Pitch Recongnition in Humans" by Drayna, Manichaikul, de Lange, Snieder, and Spector

Hypothesis:  Like addiction, genetics will have a large effect on pitch perception ability in humans.

Sample size: 136 sets of monozygotic apart twins and 136 sets of dizygotic twins

Summary of findings:  "Variation in musical pitch recognition is primarily due to hereditary differences."

**What do you think...?  (Only answer one of the final two questions.)