1. Nature & Nurture
Dr. Carolyn R. Fallahi

2. Nature-Nurture Which is more important? The Diathesis stress model
We figure out the relative amount of nature (genetics, biology, chemistry) & nurture (environment).
Problem: both diatheses & stressors are on a continuum.

3. Liability/threshold model
Schizophrenia example.
Genetic liability to Schizophrenia.
Environmental stressors may accumulate over time = total liability.
Cross the threshold = develop the disorder.
Protective factors.
Lesser forms of the disorder.

4. Study Techniques Twin Research
Identical versus fraternal twins (monozygotic versus dizygotic)
Shared environmental experiences
Common experiences, e.g. parent’s personality, intelligence, SES status, neighborhood live in, parenting techniques
Nonshared environmental experiences
Child’s own experiences within and outside the family that are not shared with siblings

5. Epigenetic View The interaction of heredity and environment.
Heredity directs the kind of environmental experiences a person has.
There is ongoing bidirectional interchange.
For example, the development of hearing and eyesight.

6. The study of Feral Children
Wild children who have been separated from society.
The Case of Genie.
Other cases.

7. Behavioral Genetic Studies
Intelligence: overall heritability of IQ scores is about .50 or 50% of the variance is explained.
Identical twins raised together: .86
Raised apart: .72
Fraternal twins: .60 & .52
Biological siblings: .47 & .24
Biological parent & child: .42 & .22
Adopted parent & adopted child: .19

8. Temperament & Personality
Temperament: a set of tendencies to respond in predictable ways.
Buss & Plomin (1984) found .50 to .60 average correlations between temperatment scores of identical twins. The correlations for fraternal twins are about 0.

9. Psychological Disorders
Schizophrenia: disturbances in logical thinking, emotional expression, social behavior.
Originally: thought due to a cold and inconsistent mother.
Now: concordance rates for identical twins: 48%; fraternal twins 17%.
1% of the general population has Schizophrenia.