First%20Thing:%20What%20are%20some%20perceived%20traits%20that%20you%20share%20with%20mom/dad/brothers/sisters.

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First ThingWhat are some perceived traits that
you share with mom/dad/brothers/sisters.
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Objective 3.1

• to what extent does genetic inheritance
  influence behavior.
• Essay Question

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Principle 4

• Genetic predispositions may affect behavior and
  or mental processes.
• Our behaviors have an evolutionary explanation
  and have been passed from generation to
  generation through the process of natural
  selection.
• These behaviors are genetically inherited and
  play a role in human behavior.

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Nature vs. Nurture

• It has long been known that certain physical
  characteristics are biologically determined by
  genetic inheritance.
• Color of eyes, straight or curly hair,
  pigmentation of the skin and certain diseases
  (such as Down Syndrome, Autism, etc.) are all a
  function of the genes we inherit. 
• Other physical characteristics, if not
  determined, appear to be at least strongly
  influenced by the genetic make-up of our
  biological parents.

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The importance of Nature

• Genes are carried by threadlike bodies called
  chromosomes found in the nucleus of all cells.
  Humans have 23 pairs.
• Genes are often called the blueprint for life,
  because they tell each of your cells what to do
  and when to do it genes can potentially dictate
  many of our biological processes, which in turn
  can influence our behavior.

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The importance of Nature

• Height, weight, hair loss (in men), life
  expectancy and vulnerability to specific
  illnesses (e.g. breast cancer in women) are
  positively correlated between genetically related
  individuals. 
• These facts have led many to speculate as to
  whether psychological characteristics such as
  behavioral tendencies, personality attributes and
  mental abilities are also wired in before we
  are even born.

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Genetic Influence on behavior

• Understanding differences in human behavior has
  traditionally been done from two perspectives
  the nature approach that emphasized genes and
  inborn characteristics, and the nurture approach
  that emphasize learning, experience and the
  environment. This was the origin of the
  nature/nurture debate that spanned the 20th
  century.
• The twentieth century saw a swing between these
  two perspectives, but current thinking emphasizes
  gene - environment interplay. This will be the
  thesis of our objective.

A info on gene expression http//www.gnxp.com/MT2
/archives/003642.html
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Genetic Influence on behavior

• Psychologists now believe that an individual may
  have a genetic predisposition towards a certain
  behavior, but without the appropriate
  environmental stimuli this behavior may not be
  manifested ( e.g. a genetic predisposition
  towards depression, but a happy childhood
  environment)

A info on gene expression http//www.gnxp.com/MT2
/archives/003642.html
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Evidence from Twin Studies

• Twin studies are often used by psychologists to
  look at the influence of heredity and
  environment.
• Identical (monozygotic - MZ) twins develop from a
  single fertilized ovum so any differences between
  them must be due to environmental factors.
• Fraternal (dizydotic - DZ) twins develop from two
  separate fertilized eggs and are no more similar
  genetically than brothers and sisters

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Twin Studies

• Identical twins serve as excellent subjects for
  controlled experiments because they share
  prenatal environments and those reared together
  also share common family, social, and cultural
  environments.
• Furthermore, studies of twins can both point to
  gene effects and also estimate heritability, a
  term that describes the magnitude of the genetic
  effect.

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Twin Studies

• Some of the most conclusive twin study research
  has analyzed identical and fraternal twins who
  were raised apart.
• Researchers have sought to establish whether
  characteristics such as personality traits,
  aptitudes, and occupational preferences are the
  products of.nature or nurture

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Twin Studies

• Similar characteristics among identical twins
  reared apart might indicate that their genes
  played a major role in developing that trait.
• Different characteristics might indicate the
  oppositethat environmental influences assume a
  much stronger role. By comparing identical and
  fraternal twins, investigators can investigate
  the extent to which genetic inheritance
  influences behavior.

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The Minnesota Twins Studies

• In the most widely publicized study of this type,
  launched in 1979, University of Minnesota
  psychologist Thomas Bouchard and his colleagues
  have chronicled the fates of about 60 pairs of
  identical twins raised separately.
• Some of the pairs had scarcely met before
  Bouchard contacted them, and yet the behaviors
  and personalities and social attitudes they
  displayed in lengthy batteries of tests were
  often remarkably alike.

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The Minnesota Twins Studies

• http//www.cleanvideosearch.com/media/action/yt/wa
  tch?videoIdqw3S35wGgT8

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The Minnesota Twins Studies

• The first pair Bouchard met, James Arthur
  Springer and James Edward Lewis, had just been
  reunited at age 39 after being given up by their
  mother and separately adopted as 1-month-olds.

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The Minnesota Twins Studies

• Springer and Lewis, both Ohioans, found they had
  each married and divorced a woman named Linda and
  remarried a Betty.
• They shared interests in mechanical drawing and
  carpentry their favorite school subject had been
  math, their least favorite, spelling.
• This type of twin study research has consistently
  suggested that genes can play an important role
  in our behaviors. But is it the only factor?

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Things to consider

• It is often difficult to separate the relative
  influences of heredity and environment on human
  characteristics.
• People who have similar genetic makeup (e.g.,
  brothers and sisters, parents and their children)
  typically live in similar environments as well.
  So when we see similarities in behavior among
  members of the same family, it is hard to know
  whether those similarities are due to the genes
  or to the environments that family members share.
• Nevertheless, a significant body of research
  tells us that both heredity and environment
  affect behavior.

A info on gene expression http//www.gnxp.com/MT2
/archives/003642.html
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Things to consider

• In practice hardly any psychologist today accepts
  either of the extreme positions.  There are
  simply too many facts on both sides of the
  argument which are inconsistent with an all or
  nothing view. 
• So instead of asking whether child
  development is down to nature or nurture the
  question has been reformulated as How much? 
  The reality is that genes and the environment
  create a chemical cocktail that influence
  behavior.

A info on gene expression http//www.gnxp.com/MT2
/archives/003642.html
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Example of Gene-Environment interplay

• Thus far it has been established through
  research and various studies that genetics can
  influence aggressive behavior. However,
  researchers also agree that there is an
  environmental component that needs to be
  examined. Thus, it safe to safe that environment
  research is just as important as genetic
  research. Environment enrichment research can
  also be used to support this idea.
• Social Learning theory (1965)
• Bandura (1965), claims that aggressive behavior
  is learned through observing and imitating
  aggressive other people. His research study
  powerfully demonstrated the social aspects of
  aggressive behaviors. We shall look at this study
  in more detail under the Sociocultural level of
  analysis.

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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 an angry response
from his parents. A stressful environment can
trigger genes to manufacture neurotransmitters
leading to depression.