Nature Versus Nurture What Makes you Who you Are? Genetic Influence = Nature Humans are 99.95 % identical Environmental influence = Nurture

Genes: Our Biological Blueprint Genes (DNA that form chromosomes) are the units of heredity. Chromosomes threadlike structures made of DNA that contain the genes 46 in each cell Most characteristics are determine by final sex chromosome (women XX or men XY) Dominant More active in influencing a trait (brown eyes) Recessive Only influences a trait when paired with identical gene

Genes: Their Location and Composition In the nucleus of every cell we have 46 chromosomes……

Chromosomal Abnormalities Turner’s syndrome Single X Klinefelter’s syndrome extra X…(XXY) Down syndrome extra chromosome on 21st pair.

Evolutionary Psych Certain traits are selected for and come to prevail over time Seeks to explain why humans act the way they do. Useful in raising the “why of behavior”

Look at our Behaviors… Can you answer these questions using evolutionary psychology? Why do infants fear strangers when they become mobile? Why are most parents devoted to their children? Why do we divide people into categories? Why do we have more phobias about spiders and snakes than electricity and nuclear weapons? Now, the big one?

Criticisms of evolutionary perspective Start with an effect and then work backward Underestimates cultural expectations and socialization Absolves people from taking ethical responsibility for sexual behavior

Behavior Genetics Behavior Genetics Focus on individual differences & extent to which we are shaped by genes & environment Our genes effect how our environment reacts to and influences us. -Nature enables nurture

Twin Studies

Identical Twins Fraternal Twins develop from a single fertilized egg that splits in two, creating two genetically identical organisms Fraternal Twins develop from separate eggs genetically no closer than brothers and sisters, but they share the fetal environment What are the different types of twins? Identical twins Fraternal Same sex only Same or opposite sex

Cross-Sectional Studies Research Methods Cross-Sectional Studies Longitudinal Studies Participants of different ages studied at the same time. One group of people studied over a period of time.

Twin Studies: The results To summarize the countless amount of studies: twins (especially identical), whether or not they are raised in the same environment are very much alike in many ways. Genes matter- discovery of identical twins separated at birth show similarities (Bouchard twins)

Adoption Studies People who grow up together, whether biologically related or not, do not much resemble each other in personality. Adoptees traits bear more similarities to their biological parents than to their adoptive. Environment factors shared by the family have little impact on personality.

Temperament a person’s characteristic emotional reactivity and intensity Emotionally reactive 3 yr olds developed into more impulsive/ aggressive 21 yr olds What influences a person’s temperament is heredity.... Heredity Trait that is capable of being passed down.

Hereditability As environments become more similar, heredity as a source of differences becomes more important. If all schools were uniform, all families loving, heritability (differences due to genes) would increase. (differences due to environment would decrease)

Gene- Environment Interaction Our genetically influenced traits affect how people react to and influence us Physical traits (height eye color) interact with envion. To influence things like popularity, etc As we grow older we select environments suited for our genes Genes react/work in conjunction with environment Twins with ident. genes but differing experiences have similar but not ident. behavior

We’re the product of both nature and nurture; our genes give us our biological potential; our environment, including culture, determines how we express it. Children who aren't loved don’t grow. Children who have irritable natures may be harder to nurture. Intelligence is in our nature, but success depends on nurture. Every human being inherits certain behavioral tendencies that helped our human ancestors survive and thrive, but what triggers these tendencies and how often they expressed varies across cultures and individuals.

Epigenetics Study of changes in gene activity that do not involve alterations in genetic code. Biological response to environmental stressor May be passed to future generations Markers activate genome and switch genes on/off Bad Evidence that lifestyle choices can alter markers Gene of obesity to express themselves strongly vs. genes of longevity to express themselves weaker Good Learning to manipulate markers in lab Treat illness – remove stressor marker will fade

Environmental Influence Genetic influences predict ~40-50% of individual variation How much should we blame our parents? Experience does help develop brain’s neural connection Pruning Without experience a child’s brain develops 20-30% smaller

Critical Period Specific time period during development when a particular event has its greatest consequence Occur when presence of certain kinds of environmental stimuli are necessary for development to proceed normally Konrad Lorenz Imprinting Has to occur within day of hatching Konrad Lorenz studied grey geese – within 36 hours imprint on the first thing moving it sees (His black boots). Essential for life and survival. Occurs within a fixed time period. In humans – starts before birth (recognizing parents’ voices) and occurs shortly after birth.

Brain cells is an impoverished environment.

Brain cells in an enriched environment.

Experience affects brain development Impoverished environment Rat brain cell Enriched

What does this mean for humans? If children are given stimulating infant care, they score better on intelligence tests by age 12 than counterparts. Use it or lose it

A Trained Brain A well-learned finger-tapping task activates more motor cortex neurons (right) than were active in the same brain before training (left)

Gender We already know the nature differences. Focuses on SEX: XX v XY Focuses on SEX: We are going to discuss GENDER: What is the difference?

Gender Roles vs. Gender Identity Role: Our expectations about the way men and women behave Identity: our sense of being male/female How do roles develop? Social Learning Theory: learn gender-linked behavior by observation and reward or punishment Examples? Gender Schema Theory: learning what it means to be a particular gender through cultural experiences

Changing Attitudes about Gender Roles

Gender Identity Our own sense of male or female. We realize our gender identity through gender-typing: acquiring gender (masculine/feminine) roles

Dr. Money & The Boy Without A Penis Can A Boy Be Raised as A Girl?- Look into the theory of Gender Neutrality How much of our gender identity is formed by nature and how much by nurture? Dr. Money & The Boy Without A Penis

David Reimer Reflection Reflect on the ethics in the particular case, citing specific guidelines discussed in the prologue of your book, and your insights.