Chapter 3Nature, Nurture,

and Human Development

Behavior Genetics

• Behavior Geneticists - Weigh the effects of our environment and heredity• The basics• Humans have 46 chromosomes (23 from mom/23 from dad)• Chromosomes contain DNA• Genes are small parts of the DNA• Genomes – complete instructions for making an individual (all the genetic

material)

• If specific genes can be identified with disorders, gives a biological understanding

Genetics

http://www.cbsnews.com/news/many-more-genes-linked-to-autism/

Twin & Adoption Studies• Identical twins • don’t just look the same• Come from one egg and are

“genetically” identical

• Fraternal twins• Come from two eggs• Genetically no more similar

than ordinary siblings

• Adoptive Children• Resemble biological parent

personality (thinking, feeling, acting)• Resemble adoptive parent values,

attitudes, manners, faith, politics

Temperament Studies

• Temperament • Emotional excitability

• Apparent soon after birth• Tends not to change even into adulthood• More heredity here than environment

Heritability

• Heritability• How much the difference between people can be attributed to genes

• Groups• Individual gene differences don’t necessarily explain differences in groups

Parents and peers• Prenatal (before birth) conditions can affect the child• Experience modifies the brain• Unused synapses degenerate (impoverished vs enriched environment)• Lacking visual experience early, prevents normal usage later even with

surgery

• Parents…• Influence manners, political & religious beliefs• Not so much influence on personality

• Peers…• Attempt to fit in (conformity)• Influence cooperation and interaction

Cultural Influences• Culture• Behaviors, ideas, values, traditions shared in a group

• Cultural differences• Personal space• Expressing feelings• PDA• Pace of life• Educating & rearing children

• Genes lead to culture change?• Nope – culture changes faster than genes

Cultural Influence

• Individualism (Independence) vs Collectivism (Interdependence)• US, Canada, Western Europe value the individual & personal achievement• Many part of Asia and Africa value interdependence and tradition

• Cultures may be different but genetic profiles are the same

Gender Development

• Let’s read a book…

Info about the book…

• When do you think this was published?• Published in 1970

• Intended as a satire

Gender Development

• Differences• 45 Chromosomes are unisex• Biologically

• body fat• muscle,• height,• age of puberty • life expectancy

• Psychologically • More women diagnosed w/depression• More men diagnosed antisocial personality disorder

Gender Development

• Aggression• In many cultures & ages, men tend to be more aggressive

• Social Power• Most societies are male dominant

• Social Connectedness• Women tend and befriend• Men emphasize freedom and self-reliance

• Nature of Gender• Biological sex determined by 23 pair of chromosomes• Mom=X Dad= X or Y• XX=Female XY=Male

Gender Development

Nurture of Gender• Gender Roles • Expectation of how men & women should behave

• Gender Identity • One’s sense of being male or female

• Social Learning Theory • Assumes gender behavior is learned (observed & imitated) though reward

and punishment like

• Gender Schema Theory• Proposes we learn a cultural “recipe” of how to be male/female and adjust

behavior accordingly

Got time?

• “Like a girl” videoVideos\P_G Do Things Like A Girl.mp4