When we talk about genetics, we are talking
about what makes you… you!
 We are all beautiful unique snowflakes
(awwww!) but our genes made us that way.
 The species Homo sapiens have members
that are leaves of one tree… commonalities
between us.
 Our shared brain architecture allows us to
sense our world, develop language and feel
hunger all the same.
 The question comes from how much do our
genes influence our outcome versus our
environment?
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Behavior Genetics: Predicting
Individual Differences
Behaviour Genetics  the study of the
relative power and limits of genetic and
environmental influences on behavior.
 Will Angeline Jolie and Brad Pitt’s kids
grow up to be actors?
 Environment  every non-genetic
influence, from prenatal nutrition to the
people and things around us.
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Genes: Our Codes for Life
Crash Course Genetics:
Humans have 46 chromosomes in each of
their cells nuclei.
 23 from the father (sperm, 23 from the
mother (egg).
 Chromosome  threadlike structures
made of DNA molecules that contain the
genes.
 DNA  a complex molecule containing the
genetic information that makes up the
chromosomes. AKA Deoxyribonucleic Acid
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Genes  the biochemical units of heredity
that make up the chromosomes; segments
of DNA capable of synthesizing a protein.
(Beads on the necklace)
 Genes can be active or expressed, or
inactive, and not express.
 Genome  the complete instructions for
making an organism, consisting of all the
genetic material in that organism’s
chromosomes. (Whole necklace)
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Environmental events ‘turn on’ genes,
causing proteins to be made, which in
turn are the building blocks of the
physical environment.
 Genetically speaking, every other
human being on Earth is 99.9% the
same as you. Every chimpanzee is
about 96% the same as you.
 We share half of our genes with the
banana for PETE SAKE!
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Twin and Adoption Studies
Studies usually involve controlling either
the home environment while varying
hereditary OR controlling hereditary
while varying the home environment.
 Unethical to set this up in real life, so
case studies are the best way to go.
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Identical Twins  twins who develop from
a single fertilized egg that splits in two,
creating two genetically identical
organisms.
Natures human clones!
Although identical twins have the same
genes, they don’t always have the same
number of copies of those genes. Explains
why one twin only can get a disease.
Most identical twins share 1 placenta
during development. 1 in 3 cases has 2
placentas, 1 for each twin. Explains some
differences in identical twins later on.
Sometimes called monozygotic twins.
Fraternal Twins  twins who develop
from separate fertilized eggs. They are
genetically no closer than brothers and
sisters, but they share a fetal
environment.
 Sometimes called dizygotic twins.
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Identical Versus Fraternal Twins
University of Minnesota study on the
‘Jim Twins’ – follow along pages 97-98
 Separated twins are more likely to be
similar if they are identical, rather than
fraternal.
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The disclaimer – ‘ The plural of
anecdote is not data’
 If any 2 strangers were to spend hours
comparing their behaviours and life
histories, they would probably discover
many coincidental similarities.
 Twin studies can be highly criticised for
this reason.
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Twins growing up apart:
https://www.youtube.com/watch?v=Wd5
Y3-F79LY
 Nature vs Nurture Twins
 https://www.youtube.com/watch?v=bRK
bZtpBcgI
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Biological VS Adoptive Relatives
Difference between biological relative
(biological parents and siblings) and
environmental relatives (adoptive
parents and siblings).
 The question comes from are adopted
children more like their biological
parents that gave them their genes, or
like their adoptive parents who
contributed the home environment?
 NATURE VS NURTURE
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When studying adoptive families, it is
shown that people who grew up
together, whether biologically related or
not, do not resemble one another in
personality.
 In traits such as extraversion and
agreeableness, adoptees are more likely
to be like their biological, rather than
adoptive parents.
 The environment shared by a family’s
children has virtually no discernible
impact on their personalities.
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The genetic leash may limit the adoptive
family’s environmental influence, but
universally, parents DO influence their
children’s attitudes, values, manners,
faith and politics.
 Due to the fact that adoptive parents are
screened before adoption takes place,
divorce, child abuse and neglect are
less than in biological families.
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Why are children in the same family so
different?
 DISCUSS!
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Heritability
Heritability  the proportion of variation
among individuals that we can attribute to
genes. The heritability of a trait may vary,
depending on the range of populations and
environments studied.
 Differences among people.
 For example, using twin studies, behaviour
geneticists can mathematically estimate
the likelihood of a person inheriting a
genetic trait from their parents.
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Keep in mind, although we can use
heritability to predict the outcome of a
gene, we cannot say it contributes a
certain percent overall to personality and
behaviour.
 Rather, heritability refers to the extent to
which difference among people are
attributable to genes.
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Boys Raised in Barrel Study
Mark Twain jokingly
proposed to raise boys
in barrels, feeding them
through a hole up to the
age of 12.
 If we were to actually do
this the boys would all
emerge with lower than
normal intelligence
scores.
 Yet, given their equal
environments, their
scores would only be
explained by their
heredity.
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Group Differences
Heritable differences between individuals
does not imply heritable group differences.
Ex) group differences between men/women,
different races, etc.
 For example, height and weight are highly
heritable, yet nutritional influences, rather
than genetic influences (the genes have not
changed) explain why, as a group, today’s
adults are taller and heavier than those a
century ago.
 Environment acts on genetics.
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Heritability – The Nature vs
Nurture Debate
of adaptation – ex) both of
our eyes will develop the same in any
sort of environment. However, walk
around barefoot all summer, the feet
will adapt to be rough – biological
adaption to friction.
 Our shared biology enables our
developed diversity.
 Nature and nurture work together
 Influence
Genes are self-regulating –
rather than act like the blueprint that lead to the same
result no matter the context,
genes react.
 People with identical genes
but differing experiences have
similar but not identical
minds. Ex) Identical twins
who marry different spouses
with different personalities.
 Eating disorders are
genetically influenced; Some
individuals are more at risk
than others… But culture
influences what we see, and
can cause those disorders to
express more in different
societies.
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Genes and experience are both important.
They interact  the interplay that occurs when
the effect of one factor (such as environment)
depends on another factor (such as heredity).
Environments trigger gene activity 
genetically inherited traits invoke expression in
other people as well. Called Evocative
Interactions.
Think of how parents may treat each of their
children differently – child's nature and parents
nurture interact.
Aggressive student causes normally calm
teacher to lose it.
So what’s the big deal Teacher
Lady?
From conception onward, we are the
product of a cascade of interactions
between our genetic predispositions
(NATURE) and our surrounding
environments (NURTURE).
 Our genes affect how people react to
and influence us.
 Biological appearances have social
consequences.
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Gene Environment Interaction –
Why do we respond differently to
Will Ferrell than to Channing
Tatum?
FORGET
NATURE
VS NURTURE….
THINK NATURE
VIA NURTURE!!!
Molecular genetics
Goal is to identify specific genes that
influence behaviour.
 Molecular Genetics  the subfield of
biology that studies the molecular structure
and function of genes.
 The goal of molecular behaviour genetics
is to find some of the many genes that
influence normal human traits, such as
body weight, sexual orientation and
extraversion, and to explore how
mechanisms control the expression of
those genes.
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This also comes into play when predicting,
understanding and researching genetically
inherited diseases.
Molecular geneticists team with psychologists
to find the genes associated with:
Learning disabilities
Depression
Schizophrenia
Alcohol dependence
Bipolar disorder
Connect DNA of families with history of the
disease with scientists to do research on
specific genes.
Allow families to know outcomes of fetuses
before they are born.
Will labelling a fetus with a ‘risk of’ a
psychological disorder lead to
discrimination? Or will it allow supports
to be put in place early on?
 India/China debate
 DISCUSS!
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Evolutionary Psychology
Evolutionary Psychology  the study of
the evolution of behavior and the mind,
using principles of natural selection.
 Natural Selection  the principle that,
among the range of inherited trait
variations, those that lead to increased
reproduction and survival will most likely
be passed on to succeeding
generations.
 Proposed by Charles Darwin
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Natural Selection 101
Organisms' varied offspring compete for
survival.
 Certain biological and behavioural
variations increase organisms’
reproductive and survival chances in
their particular environment.
 Offspring that survive are most likely to
pass their genes to ensuing generations.
 Population characteristics change over
time.
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What does the fox say?... Er…
how does it evolve?
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Foxes = wild animals
Wolves were wild animals… bred, over time, into
domesticated dogs for specific traits 
Sheepdogs herd, Retrievers retrieve and Trackers
track, etc.
Can we do the same with foxes? YUP!
Over 30 generations of foxes, the tamest of the
bunch were bred together. This trait was
SELECTED for.
40 years and 45,000 foxes later = domesticated
foxes.
You can have a fox as a house pet in Russia..
OMG!
Domestication of Foxes in Russia

http://documentarystorm.com/dogsdecoded/
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36 minute mark
Over time, nature will select
advantageous variations from among
mutations  the random error in gene
replication that leads to a change.
 This creates new gene combinations in
each human.
 Humans are able to ADAPT to
environmental conditions, based on their
genes. This measures their level of
FITNESS. (aka Survival of the Fittest)
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Evolutionary Psychology
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https://www.youtube.com/watch?v=vJdc
9zGYVjU
Evolutionary Success Helps Explain
Similarities
 Behaviors
that contribute to
survival are found throughout
cultures.
 Name some survival
behaviors.
Evolutionary Success Helps Explain Similarities
Outdated Tendencies
 Genetic
traits which helped our
ancestors survive may harm us
today.
 Explain why this picture is
included.
Evolutionary Success Helps Explain Similarities
Evolutionary Psychology Today
 The
application of Darwin’s ideas
in the science of psychology has
been called“the Second
Darwinian Revolution”.
How does Evolution help
Psychologists?
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This ‘second evolution’ has allowed psychologists
to address questions such as:
Why do infants start to fear strangers about the
time they become mobile?
Why are biological fathers so much less likely than
unrelated boyfriends to abuse and murder the
children with which they share a home?
Why do so many people have phobias about
spiders, snakes, heights than about more
dangerous threats like guns and electricity?
Why do humans share some universal moral
ideas?
DISCUSS!
An Evolutionary Explanation of Human
Sexuality
Gender Differences in Sexuality
Studies suggesting
men have a stronger
tendency towards
sex.
 Desire sex more
frequently, think more
about sex, initials
more sex and will
sacrifice more to gain
sex.
 Lower threshold for
perceiving warm
responses as a
sexual come on.
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An Evolutionary Explanation of Human Sexuality
Natural Selection and Mating Preferences
 Differing preferences in partners
 Male preferences – recreational, pair
widely, attracted to youthful
appearance, healthy, fertile
appearing, waist 1/3 narrower than
hips, age of peak fertility.
 Female preferences – relational, pair
wisely, attracted to mature, dominant,
bold, affluent men, potential for long
term mating, investing in joint
offspring.
Nature Selects behaviours that increase
the likelihood of sending one’s genes
into the future, whether you are male or
female.
 https://www.youtube.com/watch?v=iGoC
8FTLKSI
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Critiquing the Evolutionary Perspective
theorizing –
Paragraph 1, page 107
 Impact of social influence –
roles have changed over time.
 Backward