PSYCH 9C Lecture Notes - Lecture 3: Nomothetic, Meta-Analysis, Extraversion And Introversion
Lecture 3:
Where Does Personality Come From?
Personality is Rooted in Genetics
●The genetic influence on personality is about 40-60%;
highly dependent on genes
●Environmental effects?
Traits and The Environment
●Between family Effects (shared environment)
○Very little relationship between adoptive siblings and
their adoptive parents
○Twins raised together vs. raised apart
○There is little effect of SHARED environment; little
impact on personality. Adopted siblings are not very
alike in personality. The same is true for adoptive
parents.
●Within family Effect (non-shared environment)
○Environments of children within a family differ
○Birth order
○Non-shared > shared environment; this signifies that
there is more of a genetic basis for personality.
Identical Vs. Fraternal Twins
●Identical (monozygotic) twins share 100% of their genes
●Fraternal twins (dizygotic) twins share 50% of their genes
○The same as any two siblings
○Generally more common
●Both types share the same prenatal environment; identical
twins are in the same placenta, but different amniotic
sacs. Fraternal are in different placenta.
Traits and Biology
●Personality much more correlated for identical twins
●Biology is very important in personality
BUT…
●Parents are still important
○Minimal level of nurturing required for a person to
have proper socialization so as not to become a
delinquent, and for the child to thrive.
Temperaments are Evident in Infancy
●Broader than personality traits; general tendencies to feel
or act in certain ways. You usually talk about them in
terms of children. Our temperament as children lead to
adult personalities.
●Three Basic Characteristics
○Activity level: energy/behavior
○Emotionality: intensity of emotional reactions
○Sociability: Tendency to affiliate/be with others
■Linked to people acting in certain ways
●People more active as children were more
likely to move away from hometown
●High in emotionality move to places very
close to their hometown, or a few streets
away
●High in sociability likely to move to urban
areas, densely populated places
○Children’s temperaments are linked to
adult behaviors
Long Term Implications of Temperaments
●Predict personality structure and behaviors
●Inhibition at 2 months of age are more shy when they are
adults; children less likely to explore environment and
look people in the eyes, not likely to show positive
emotions, and more responsive to stress.
●Babies that showed a lot of motor movement in response to a
stimulus is more likely to be shy because he had high
baseline arousal. He is very easily aroused by the mobile,
so he is more likely to be shy as an adult.
●Babies that are not very aroused at the stimulus are more
likely to be outgoing as adults because they have a higher
baseline arousal.
Not All Biological
Document Summary
Personality is rooted in genetics highly dependent on genes. The genetic influence on personality is about 40-60%; Very little relationship between adoptive siblings and their adoptive parents. There is little effect of shared environment; little impact on personality. Adopted siblings are not very alike in personality. Environments of children within a family differ. Non-shared > shared environment; this signifies that there is more of a genetic basis for personality. Identical (monozygotic) twins share 100% of their genes. Fraternal twins (dizygotic) twins share 50% of their genes. Both types share the same prenatal environment; identical twins are in the same placenta, but different amniotic sacs. Personality much more correlated for identical twins. Minimal level of nurturing required for a person to have proper socialization so as not to become a delinquent, and for the child to thrive. Broader than personality traits; general tendencies to feel or act in certain ways. You usually talk about them in terms of children.
