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

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Presentation on theme: "First Thing: What are some perceived traits that you share with mom/dad/brothers/sisters."— Presentation transcript:

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


3 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.

4  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. Nature vs. Nurture

5  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. The importance of Nature

6  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. The importance of Nature

7  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 20 th 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. Genetic Influence on behavior A+ info on gene expression

8  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) Genetic Influence on behavior A+ info on gene expression

9 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 Evidence from Twin Studies

10  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. Twin Studies

11  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 Twin Studies

12  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 opposite—that environmental influences assume a much stronger role. By comparing identical and fraternal twins, investigators can investigate the extent to which genetic inheritance influences behavior. Twin Studies

13  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. The Minnesota Twins Studies

14  media/action/yt/watch?videoId=q w3S35wGgT8 media/action/yt/watch?videoId=q w3S35wGgT8 The Minnesota Twins Studies

15  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. The Minnesota Twins Studies

16  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? The Minnesota Twins Studies

17  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. Things to consider… A+ info on gene expression

18  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.child development Things to consider… A+ info on gene expression

19  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. Example of Gene-Environment interplay

20 20 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.

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