AP Psychology Unit 1 - Interaction of Heredity & Environment

Behavioral Genetics

The study of how genetic inheritance and environmental factors influence behavior and psychological traits.

Genetic Inheritance

The process by which genes are passed from parents to offspring, affecting various traits and characteristics.

A child has a 50% chance of inheriting a specific gene from their parent. Ranges from 100% for identical twins and 6.25% for second cousins.

Genotype

A person’s genetic makeup

Is also determined at conception and will remain the same forever

Phenotype

A person’s physical traits

May change over time from environmental factors

Chromosomes

Structures within cells that contain DNA and genes, determining genetic traits. Chromosomes are made up of DNA, organized into pairs, and are responsible for heredity.

Humans have 46 chromosomes, inheriting 23 from each parent

Identical Twins

Twins who develop from a single fertilized egg that splits into two embryos, sharing the same genetic material.

Fraternal Twins

Twins who develop from two separate fertilized eggs, each sharing only about 50% of their genetic material.

Example: Twins of the opposite sex

Epigenetics

The study of changes in gene expression that do not involve alterations to the underlying DNA sequence, often influenced by environmental factors.

Certain gene effects can be silenced by environmental triggers. This is caused when a methyl group, which is attached to each DNA molecule, which can turn gene expression on or off.

Known study from Michael Skinner involved a study where exposing rats to DDT left them with a higher rate of getting certain diseases, which affected the traits of multiple generations of rats.

Natural Selection

The process by which traits that enhance survival and reproduction become more common in successive generations of a population.

Eugenics

A pseudoscience that valued genetic purity and discriminated against those with undesirable traits