Nature vs. Nurture
• Behavior Genetics
– The study of the influences of heredity and the
environment on behavior
– “Nature”
Our genetic influences
– inborn traits
vs.
“Nurture”
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 birth
Same “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.