lecture 9 Flashcards
Gene and environment interaction
Genetically different individuals will have different experiences to the same enviromenatl stimuli. (The effect of the environment on phenotype will depend on genotype and the effect of genotype on phenotype will depend on enviroment.)
Types of interactions: 1. Diathesis-stress model
Individuals who are especially sensitive to the effects of stressful enviroments (vulnerable genes)
Types of interactions: 2.Vantage sensitivity
Individuals gaining more than others from a good enviroent because they are more sensitive.
Types of interactions: 3.Differential Susceptibility framework (the most realistic)
Individuals are sensitive to both negative as well as posiitive infleunces ( plasticity of genes)
Gene and environment interaction studies:
-It is usually unethical and whenever it is ethical big data size is required so mostly done on plants and animals.
- Instead, scientists design weaker studies where they look at the heritability of traits in different environments.
Human research of gene and environment interaction findings:
1-Children are born with all of their genes
2- some studies found heritability differs between different socioeconomic levels: rich people have more heritability while the poor has less.
The transactional model of cognitive development
Children choose and create experiences that match their natural traits. These experiences then help their thinking skills grow, making the effects of their genes on learning even stronger over time.
Possible reasons for different socioeconomic levels having different heritability levels: 1.The Scarr-Rowe hypothesis
A supportive environment (high SES) enlarges the difference between individuals with higher and lower genetic predispositions. (still unclear)
Possible reasons for different socioeconomic levels having different heritability levels: 1. Compensatory Advantage Hypothesis
High SES compensates for genetic challenges.
-There might be no gene environment interaction.
- Maybe the social environment doesn’t let people choose freely.
Missing heritability
Big and obvious gap between the heritability estimates from twin/family studies and the heritability captured by polygenetic signals from GWAS (which is smaller)
Candidate gene studies
1- It is a flawed approach.
2-focuses on specific genes thought to be linked to a trait.
3- Even when there is an effect, it explanins less than 0.1% pf the variation.
4-Many studies report gene-enviroment interaction unreliable.
5- What is the better alternative? GWAS!
Why is finding genes difficult?
1-Measurement error of phenotype + multiple definitions of traits.
2- Multiple genes with small effects.
3-Interactions and correlations with the environment.
Endophenotype (intermediate phenotype)
measurable trait that connects genes to a condition or behavior. It is something you can observe in the body or brain that helps explain how genetics influence complex traits like mental health disorders.
