Nature vs. Nurture

• Behavior Genetics– The study of the influences of heredity and the

environment on behavior

– “Nature” vs. “Nurture”

Our genetic influences – inborn traits

Environmental influences (everything non-genetic)

What makes someone…

A superior athlete?

What makes someone…

Funny?

What makes someone…

Mean, cruel, or evil?

What makes someone…

Intelligent?

What makes someone…

Brave?

What makes someone…

Shy? or outgoing?

Is it “nature”

or “nurture”

?

Adoption Studies

Is the child more like the biological parents (“nature”) or adoptive parents (“nurture”)?

? ?

Twin Studies

Can compare identical twins with fraternal twins

Monozygotic = identical twins (one egg, exact same genetics)

Dizygotic = fraternal twins (two eggs, no more genetically similar than other siblings)

Twin Studies

Can study identical twins separated at birthSame “nature” … different “nurture”

Minnesota Twin Studies

• Dr. Thomas Bouchard & Dr. David Lykken– Conducted famous longitudinal studies on twins at U of M to attempt

to determine which characteristics we inherit (nature) and which we acquire (nurture)

– Included 8,000 pairs of twins born b/w 1936-1955– Hypothesis: Even if identical twins were reared apart, they should exhibit the

same traits in many areas due to the fact that they share 100% of genetic blueprint. Those traits that differed were due to environmental influences.