Nature vs. Nurture

Nature

biological influences

Nurture

environmental influences

Behavioral genetics

how genes and environment work together to shape behavior

Genes

Units of heredity that make up chromosomes (coils of DNA). When genes are expressed they provide the code for making proteins

Chromosomes

Humans have 46 chromosomes

Sex chromosomes

Females: XX

Males: XY

Inheritance

Each parent gives half of their chromosomes to offspring.

Identical twins

from a single fertilized egg; genetically identical; may or may not share a placenta

Fraternal twins

from two eggs; genetically similar like normal siblings

Why Are Siblings Different?

• They share only 50% of genes

• Genetic differences amplified by:

  • Different experiences

  • Changing family environments (birth order, parental age)

Temperament

emotional reactivity & intensity. Appears early in life and usually persists

Types of temperament and evidence

Easy, Difficult, and Slow-to-warm-up Physiological evidence: differing heart rates, nervous system reactivity

Epigenetics

Environment can turn genes on or off at the molecular level. Environmental influences begin in the womb

Synaptic pruning

unused neural connections fade. Brain remains plastic (able to change) throughout life.

Parent influence

Parents matter most in extreme situations. Research shows that shared environment (the home you grow up in) explains less than 10% of why children differ from each other.

Parent effects

Religion, values, manners, attitudes, politics, habits

Parent influence on development

Education & career path, responsibility, self-discipline, cooperation, charitableness, interaction with authority

Peer influence

Cooperation skills, popularity dynamics, habits, music preferences, clothing and cultural choices

Peer selection

Children often choose peers themselves; influence difficult to separate from self-selection

Culture

Shared ideas, values, habits, and traditions passed through generations

Cultural norms

Standards for acceptable and expected behavior

Culture shock

Feeling unsure of proper behavior in a new culture

Within-culture changes

Faster pace of life, tech use increases, language shifts, rising gender equality

Genetics vs culture

Cultural changes happen too fast to be genetic

Individualism

Independence, personal goals, uniqueness, self-esteem

Collectivism

Interdependence, group goals, duty, harmony, family loyalty

Individualist relationships

Many, temporary, confrontation acceptable

Collectivist relationships

Few, close, long-lasting, harmony valued

Individualist coping

change reality

Collectivist coping

Accept or adjust to reality

Individualist morality

Self-based

Collectivist morality

Duty-based, social network-based

Individualist child raising

Independence, self-reliance

Collectivist child raising

Obedience, group integration, emotional closeness

Sex

Biological category based on genotype

Gender

physical, social, and behavioral characteristics culturally associated w/ men and women. Product of interplay between biological dispositions, developmental experiences, and current situation

Androgen Insensitivity Syndrome (AIS)

XY genotype; body cannot respond to androgens; develops female traits; internal testes, no ovaries

Gender schemas

Mental frameworks children use to categorize male/female.

Gender expression

Shown in language, clothing, interests, possessions

Gender roles

Expected behaviors for each gender; shift with time and culture

Social learning theory of gender

Children learn gender by observing, imitating, and being rewarded/punished

Minor physical aggression

men and women equal

Extreme violent acts

Men commit more than women

Relational aggression 

women more likely than men

Gender and social power

Men more often in leadership; higher salaries; more political representation; women elected less often.

Gender interaction styles

Men give opinions; women offer support

Biopsychosocial approach

considers factors influencing individual development