Behavior Genetics: Predicting Individual Differences

Behavior Genetics: Study of how genetic and environmental influences shape behavior.
- Investigates individual differences in behavior stemming from shared and non-shared influences.
- Each family shares genetic tendencies and life events that influence behavior.

Chromosomes: Thread-like structures made of DNA, containing genes. Humans have 23 pairs of chromosomes (46 total), with one set from each parent.
Genes: Biochemical units of heredity that influence traits by coding for protein synthesis.
Genome: Complete set of instructions for making an organism, which consists of all genetic material in that organism.
DNA (deoxyribonucleic acid): Complex molecule containing genetic information that dictates how an organism develops and functions.

Genes can be either active (expressed) or inactive, depending on internal and environmental triggers.
Epigenetics: Study of changes in gene expression that don’t involve alterations to the DNA sequence but may still impact how traits are expressed.
- Epigenetic marks: Chemical changes that can instruct cells to disregard certain genes without changing the DNA itself.

Identical Twins (Monozygotic): Develop from a single fertilized egg that splits, thus sharing the same genetic makeup.
Fraternal Twins (Dizygotic): Develop from two separate eggs fertilized by different sperm, sharing only 50% of their genes like regular siblings.
Comparative Analysis of Twins:
- Identical twins typically show stronger similarities in personality, preferences, and even physical traits when compared to fraternal twins.
- Example: If an identical twin is divorced, the odds of the other being divorced are 5.5 times greater compared to the 1.6 times greater odds in fraternal twins.

Heredity: Refers to the proportion of variations among individuals attributable to genetics.
- Example: If heritability of intelligence is estimated to be 50%, genetic factors account for half of the variation in intelligence within a population.
As individuals share more similar environments, the impact of heredity on personality differences increases, especially in homogeneous settings.

Field of Study: Focuses on the molecular structure and function of genes.
- Aims to identify specific genes that dictate various traits such as weight, sexual orientation, and personality.
Can reveal predispositions to myriad conditions, including learning disorders, depression, and schizophrenia, based on genetic testing.

Interaction: The way in which the effect of one factor (like the environment) on behavior is influenced by genetics.
Gene-Environment Interactions: Show that environmental factors can trigger or suppress gene expression, leading to differing outcomes among individuals with similar genetics.
- Example Scenario: In a uniformly supportive environment, differences in intellectual performance may primarily reflect genetic differences rather than educational discrepancies.
Conclusion: Understanding behavior genetics involves examining the interplay of genetic predispositions and environmental factors, particularly how they influence individual variations in personality and behavior.