1. Behavior Genetics
Dr. Blakemore
PSY 235

2. Polygenic Transmission
Many traits can vary along some dimension
These kinds of traits are influenced by many (perhaps hundreds or thousands) of genes working together
Many behaviors are influenced polygenetically

3. Behavior Genetics Major methods are twin studies and adoption studies.
One common technique of the behavior geneticists is to examine the correlation between pairs of people of differing degrees of genetic relatedness.

4. Intelligence
The characteristic most studied by behavior geneticists is intelligence.
There is evidence for both genetic and environmental influences on intelligence.

5. Intelligence - Correlations
Random Pairs
Pairs of unrelated strangers - .00
Biological Relatives Living Together
Parents and their biological children - .42
Siblings - .47
Fraternal Twins - .60
Identical Twins - .86

6. Intelligence - Correlations cont’d
Living Together - Not Biologically Related
Adoptive parents - adopted children .19
Adopted siblings - .32
Biologically Related - Living Apart
Biological parents - adopted-away children .22
Identical twins reared apart - .72

7. Intelligence - All Correlations
Identical Twins - .86
Identical twins reared apart - .72
Fraternal Twins - .60
Siblings - .47
Parents and their biological children - .42
Adopted siblings - .32
Biological parents - adopted-away children .22
Adoptive parents - adopted children .19

8. Personality Several personality characteristics show genetic influence
E A S traits - temperament
E= Emotionality, A= Activity, S= Sociability
Specific fears, sensation-seeking, physical anxiety, anger, task persistence, and fidgeting