1 PSYCHOLOGY (8th Edition, in Modules) David Myers
Jan 01, 2016
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Behavior Genetics: Predicting Individual Differences
Behavior Geneticists study our differences and weigh the relative effects
of heredity and environment.
This used to be called the Nature vs. Nurture Debate
Now it is called Nature via Nurture
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Genes: Our Codes for LifeIn the nucleus of a cell chromosomes (46) containing DNA (deoxyribonucleic acid)
are situated.
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Genes: Our Codes for Life
Segments within DNA constitute genes making proteins to determine our development.
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Genome
Genome is the set of complete instructions for making an organism Containing all the
genes in that organism. Thus human genome makes us human and the genome
for drosophila makes it a common house fly.
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Genetics
• Humans have 30,000 genes.
• 99.9% of your DNA matches that of every other human
• Our genes are responsible for predisposing our appearance and behavior.
• Predisposition only means that the possibility of development of (x) exists.
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Twin Biology
To study the effects of heredity and environment two sets of twins, identical
and fraternal, have come in handy.
MonozygoticTwins
Dizygotic Twins
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Twin and Procedures
Behavior geneticists study the effects of shared and unique environments on total or partial
genetic makeup.
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Separated Twins
A number of studies have looked at identical twins raised separately from birth or close
there after and have found a number of similarities.
Separated Twins
Personality, Intelligence
Abilities, Attitudes
Interests, Fears
Brain Waves, Heart Rate
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Separated Twins
Critics of separated twin studies note that such similarities can be found between strangers. However, researchers point out that differences between fraternal twins are greater than identical twins.
Bob
Sach
a
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Adoption Studies
Opposed to twin studies, adoption studies suggest that adoptees (who may be
biologically unrelated) tend to be different from their adoptive parents and siblings.
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Adoptive Studies
Adoptive studies strongly point to the simple fact that biologically related children turn out
to be different in a family. So investigators ask:
Do siblings have differing experiences?
Do siblings, despite sharing half of their genes, have different combinations of the other half genes?
Ultimate question: Does parenting have an effect?
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Parenting
Parenting does have an effect on biologically related and unrelated children.
Parenting Influences children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics
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Temperament Studies
Temperament refers to a person’s stable emotional reactivity and intensity. Identical
twins express similar temperaments, suggesting heredity predisposes temperament.
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Heritability
Heritability refers to the extent to which the differences among people are
attributable to genes.
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Nature and Nurture
Some human traits are fixed, like having two eyes, most psychological traits are liable to
change with environmental experience.
So genes provide choices to the organism to change its form or traits when
environmental variables change. Therefore genes are pliable or self-regulating.
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Gene-Environment Interaction
Genes can influence traits which affect responses, and environment can affect
gene activity.
A genetic predisposition that makes a child restless and hyperactive, evokes angry responses from his parents. A stressful
environment can trigger genes to manufacture neurotransmitters leading to
depression.