Chapter 7: Estimating Genetic and Environmental Influences Flashcards
What is heritability?
The proportion of phenotypic variance that can be accounted for by genetic differences among individuals.
What is SNP heritability?
Heritability estimated directly from DNA differences between individuals.
What is the equation for heritability (A)?
A=2(rmz-rdz)
What is the equation for non-shared environment (E)?
E=1-rmz
What is the equation for shared environment (C)?
C=(2rdz)-rmz
What is Falconer’s Formula for phenotypic variance (Vp)?
Vp=A+C+E
What are non-shared/unique environments?
All “non-genetic influences” that are independent for family members.
What is another name for the random coefficient?
The non-shared/unique environment.
When doing a SNP heritability study, can two individuals in the study be related?
No.
What is so-called “missing heritability?”
The differences in SNP and twin estimates of heritability.
What are some limitations of Falconer’s formula? (3)
- Human behavior isn’t as simple as A,B,C - there is interplay between genes and environment. 2. Development changes over time. 3. It is an additive approach. 4. Only measures narrow-sense heritability.
What is an example of a significant result, but a very small effect size?
Birth order and IQ.
What is an example of a significant result and a high effect size?
Child emotional problems and childhood neglect.
Why does statistical significance not equal effect? (2)
- Doesn’t say anything about strength of an association. 2. Doesn’t account for limited sample size.
About how heritable are personality traits?
.40.
What is a twin correlation?
Correlation of twin 1 and twin 2.
What is twin concordance?
The presence of the same trait in both members of a twin pair.
What is twin concordance used for?
For estimating the risk for a disorder.
What is twin correlation used for?
To estimate genetic and environmental influences.
What is a genetic correlation?
A statistic indexing the extent to which genetic influences on one trait are correlated with genetic influences on another trait independent of the heritabilities of the traits.
What is bivariate heritability?
Estimates the contribution of genetic influences to the phenotypic correlation between the two traits.
What would a genetic correlation of 1 mean?
All genetic influences on trait X also influence trait Y.
