psych 102

Nature vs. Nurture: Refers to the interaction of genetics (nature) and environment (nurture).
Example: Depression in adopted individuals can be influenced by both genetic predisposition (nature) and the nurturing environment they grow up in (nurture).

Definition: The study of individual differences due to hereditary and environmental influences.
Involves measuring how genetics and the environment affect traits and behaviors.
Behavior geneticists: Specialize in studying nature vs. nurture.

Heredity: Genetic transmission of characteristics from parents to offspring.
Examples of hereditary traits: Hair color, eye color, genetic predispositions (like depression).
Environment: Non-genetic influences including family dynamics, socioeconomic status, prenatal conditions, upbringing, and social interactions.
Influence of parental behavior and community activities on a child's development (e.g., parents being active in the community).

All living organisms consist of genetic material found in every cell, with DNA containing genes.
Genes: Units of heredity determining physical and some behavioral traits.
Human beings are almost entirely genetically identical (about 99.9%).
Humans share approximately 96% of their genetic code with chimpanzees, making chimpanzees relevant in comparative psychology studies.

Over 70 trillion unique combinations of genetic traits possible due to parental genes.
Polygenic traits: Traits determined by multiple genes rather than a single gene (e.g., schizophrenia linked to about 20 different genes).

Identical twins (monozygotic): Formed from the splitting of one fertilized egg; share 100% of their genetic material.
Fraternal twins: Develop from two separate eggs fertilized by two sperm; share about 50% of genetic material.
Research investigates personality traits, interests, and disorders among twins to understand genetic vs. environmental influences.
Findings suggest those raised together do not necessarily have similar personalities, highlighting genetic over environmental influence in personality formation.

Individuals often resemble their biological relatives in personality traits more than their adoptive families.
Research indicates shared family environment has little impact unless influenced by extreme circumstances (e.g., abuse).
Parenting can influence values, social environment, attitudes, education, and not necessarily personality.

Temperament: Refers to emotional reactivity and intensity, often inherited.
Differences in sibling temperaments may arise from diverse parenting experiences or personal choices.
Temperament can be influenced by genetics but may also change over a lifetime.

Heritability: Percentage of variation among individuals attributed to genetics.
Example: Major depression has about 30% heritability.
Individual contributions to traits are complex and not easily quantified in terms of exact percentages.

Genetic and environmental factors interact to shape individuals.
Some traits are consistently developed across environments while others depend heavily on environmental context.
Epigenetics: The study of how environmental factors can influence gene expression (turning genes on or off).
Epigenetic changes can be passed to future generations, affecting their predisposition to certain traits or health issues.

Nature and nurture are interconnected; genetics set predispositions while environmental experiences may shape how these predispositions are expressed in individuals.
Just like DNA (immutable) and epigenetic factors (modifiable), both play critical roles in self and behavior development.

Understanding the balance between nature and nurture is critical in psychology, impacting personality, behavior, and mental health.
This foundational knowledge prepares for exploring more advanced psychological topics, including evolutionary psychology next lesson.