7. Nature vs Nurture Flashcards
percentage of variance
refers to the fact that individuals vary or are different from each other. and this variability can be parted into percentages that are due to different causes. ?
heritability
a statistic that refers to the proportion of observed variance in a group of individuals that can be accounted for by genetic variance.
- describes the degree to which genetic differences between individuals cause differences in an observed property such as height.
- provides useful information in identifying the genetic and environmental determinants of personality.
fancy definition: the proportion of phenotypic variance that is attributable to to genotypic variance.
phenotypic variance difference
observed individual differences such as height, weight or personality
phenotypic variance difference
pheno: observed individual differences such as height, weight or personality.
geno: individual differences in the total collection of genes possessed by each person.
example:
environmentality
the percentage of observed variance in a group of individuals that can be attributed to environmental (nongenetic) differences.
misconceptions about heritability
- Refers ONLY to differences in a sample or population NOT to an individual.
- misconception that it is constant but it aint
Clarifying Nature-Nurture debate
- knowing definition of heritability allows us to think more clearly about this.
- cake example, at an individual level: doesn’t make sense to argue which one is more important cuz to make a cake it takes eggs and flour. one is not more imp than the other
- at population level: can be logical to ask “if u bake 100 cakes and all these taste a lil different, what accounts for the differences among these cakes?
family studies
- trying to find gene similarities between family members. but then you’ll never know for sure if it is genes or the similar environment
twin studies
- estimate heritability by gauging whether identical twins who share 100% of their genes are more similar to each other than fraternal twins (50% of genes)
- jim twins separated at birth but still shared many common things
monozygotic twins
- come from a single fertilized egg
- one egg that divides
share 100% of genes
dizygotic twins
- fraternal twins
- two eggs separately fertilized
formula for calculating heritability
do we need to know this?
adoption studies
- could be most powerful behavioral genetic method available
- correlations between adopted children and their adoptive parents with who they share no genes.
- ## if a positive correlation is found it means environment plays a big factor in personality
minesota twin study
- tested 2 types of twins
- when raised together or apart
- results: monozygotic twins had more in common than dizygotic
- so genes were
environmental influences
- shared env: env that experienced the same for all children (house,food, etc)
- non shared: env that experienced differently for children (friends)
- have bigger impact on personality development
