Behavior Genetics and Twin Studies

Definition: Study of the degree and nature of heredity's influence on behavior.
Less invasive than molecular genetics or selective breeding.
Uses methods like twin studies to examine the extent individuals are shaped by heredity and environment.

Method: Compares behavioral similarity of identical twins with fraternal twins.
Identical Twins: Develop from a single fertilized egg, resulting in two genetically identical embryos, sharing $100\%$ of genetic material.
Fraternal Twins: Develop from separate eggs and sperm, genetically no more similar than non-twin siblings, sharing $50\%$ of genetic material.
Principle: By comparing correlations across identical versus fraternal twin pairs, researchers estimate how much similarity in identical twins is attributable to shared genes.
Example (Gaming Study):
- Identical twins showed greater similarity in gaming frequency than fraternal twins.
- Genetic contribution to video gaming was approximately twice as strong for boys as for girls.
Limitation: Environmental factors might influence observed similarities; adults may emphasize identical twin likeness, and identical twins might perceive themselves as a "set," leading to more shared experiences.