Transcript Behavior Genetics

Nature, Nurture, and
Human Diversity
Chapter 3
1
Nature or Nurture?
Behavior Genetics
Heredity
Environment
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Behavior Genetics: Genes
• Terms to know:
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Chromosomes
DNA
Genes
Genome
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Behavior Genetics: Twin Studies
Identical vs. fraternal => Identical more similar
Identical separated at birth => many similarities:
personality, intelligence, abilities, interests, brain
waves, etc.
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Behavior Genetics: Adoption Studies
Adoptees tend to be different from their
adoptive parents and siblings.
Adoptees’ values, attitudes => adoptive parents
Adoptees’ personalities = > biological parents
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Behavior Genetics: 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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Behavior Genetics: Heritability
Heritability: the extent to which the differences among
people are attributable to genes (vs. environment).
(NOT: Your high IQ is 50% attributable to your parents’ genes)
BIG IDEA: Nature and Nurture
- Genes are self-regulating (adaptable)
- We are products of genetic predispositions &
surrounding environments
(Naturally outgoing kids receive more attention)
The Future: Molecular Genetics
Molecular genetics: identifying functions of genes
(Issues: designer babies, weeding-out disorders, etc.)
Evolutionary Psychology
Evolutionary psychology: study of human
similarity & the evolution of behavior and mind
through natural selection (remember Darwinism?)
Biologists like Belyaev
and Trut (1999) were
able to artificially
domesticate wild foxes,
selecting them for
friendly traits.
Any trait that is favored naturally or artificially
spreads to future generations.
Evolutionary Psychology: Human Traits
A number of human traits have resulted from
natural selection.
Why do infants fear strangers when they become
mobile?
Why are most parents so passionately devoted to their
children?
Why do people fear spiders and snakes and not
electricity and guns?
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Evolutionary Psychology: Human Sexuality
Gender Differences in Sexuality
Differences in males & females arise in regards
to reproductive behaviors.
(Heterosexual or Homosexual*)
Question (summarized)
Male
Female
Casual sex
60%
35%
Sex for affection
25%
48%
Think about sex everyday
54%
19%
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Evolutionary Psychology: Mating Preferences
Males: select multiple partners => best odds of
producing offspring
(look for youthful, fertile appearance)*
VS.
Females: select one, stable partner => best odds of
producing offspring
(look for maturity, dominance, affluence, boldness)*
*Data based on 37 cultures.
Nurture: Influences
Early Experiences
• Prenatal environment
• Early postnatal experiences (remember the Rhesus monkeys?)
Nurture: Influences
Parental Influence
• Parental influence is largely genetic.
• Parental influence (+ & -) often overemphasized.
• Has most influence on: education, discipline,
responsibility, charitableness, respect
Peer Influence
• Conforming to the group
• Has most influence on: interacting, cooperation,
gaining popularity
Nurture: Influences
Cultural Influences
Culture : behaviors, ideas, attitudes, values and
traditions shared by a group (and passed-on) that
vary across time & place
• Cultural Norms: rules for accepted and expected
behavior
Can you think of
any American
cultural norms?
Nurture: Influences
Culture and the Self
Individualism (“I”) vs. Collectivism (“We”)
Westernized Cultures
Asian-African Cultures
Responsible for your self
Responsible to group
Follow your conscience
Priority to obedience
Discover your gifts
Be true to family-self
Be true to yourself
Be loyal to your group
Be independent
Be interdependent
Nature and Nurture
Gender Development
Males
Females
Nature and Nurture
Gender Development
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Nature and Nurture
Gender Development
Males
Females
Y Chromosome
Testosterone
Solitary
Play in large groups
Autocratic
Support war
More arrests
Aggressive
Antisocial personality
disorder
Hyperactivity
Alcoholism
Higher suicide rate
Estrogen
More talkative
More religious
Interdependent
Play in small groups
Democratic*
Eating disorders
More depression
Sense of smell
Dream = of men/women
Longer life span
Earlier puberty
More fat
Nature and Nurture
Gender Roles
Gender = Biopsychosocial
Gender Identity —how a person views himself
or herself in terms of gender.
How is this identity formed?
1. Social Learning Theory: we learn gender
behavior like any other behavior—reinforcement,
punishment, and observation.
2. Gender Schema Theory: we learn a cultural
“recipe” of how to be a male or a female, which
influences us; forms a “lens” for viewing the
world => male or female
Reflections on Nature and Nurture
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