Behavior Genetics: Predicting Individual Differences Module 14

We are like the leaves on a tree. 14-1 Define genes & describe how behavior geneticists explain our individual differences We are like the leaves on a tree. Imagine a building where every room has a 46 chapter book containing the plans for the building DNA is the alphabet, genes are pages, chromosomes are chapters, genomes are the books (23 chapters from Mom, 23 from Dad)

Twin & Adoption Studies Our genetic predispositions help explain shared traits & diversity. Identical twin differences?? Number of copies or separate placenta Bouchard’s Minnesota Twin Study https://www.youtube.com/watch?v=qw3S35wGgT8

ADOPTION STUDIES The environment shared by a family’s children has virtually no discernible impact on their personalities. Poker analogy – Mom might have a full house & Dad a straight flush, but mix half the cards & Junior may have this… There is actually a lack of striking differences when comparing different adoptive homes…. WHY?

14-2 What is the promise of molecular genetics research? Molecular genetics seeks to identify specific genes influencing behavior Genetic testing can now reveal at-risk populations for disease It can also be used to discriminate against the unborn or the genetically “different” Ethics of this type of research???

14-3 What is heritability & how does it relate to individuals & groups? The proportion of variation among individuals that we can attribute to genes Mark Twain’s barrel example The key thing to remember is that this refers to variation within a GROUP, it does NOT refer to the impact of nature on an individual. We can NEVER say what percentage of an individual’s traits are inherited Even among groups heritability is influenced by environment (South Korean height vs North Korean 90%, 6 inches)

14-4 How do heredity & environment work together? Nature & nurture work together like two hands clapping Genes are self-regulating…. Instead of blueprints that create the same plan each time, think of them like cards Charles Brewer- “Heredity deals the cards, environment plays the hand.”

Epigenetics – the study of environmental influences on gene expression that occur without genetic alteration