22 Behaviour, Genetics and Personality: from Galton to Bouchard Flashcards
When did Sir Francis Galton publish Hereditary Genius?
In 1869
What were Galton’s findings and conclusions in Hereditary Genius?
Findings: Prominent people have prominent relatives. The closer the kinship, the likelier the relative is to be prominent (48% sons, 7% grandsons, 1% great-grandsons).
Conclusion: genius and feeble-mindedness run in families
Who invented the term “Eugenics”
Sir Francis Galton
What did Thornhill and Palmer (2000) argue about rape?
That raping women may be an adaptation.
What did Dar-Nimrod find to be the effect on view of rapists when Pps exposed to the evolutionary argument for rape?
IN MEN… reading about the evolutionary psychology view of rape did not change evaluation of rapist from that of control group. Reading a social constructionist view created
1) a more negative view of rapist
2) rated rapist as having more control and
2) deserved harsher punishment.
IN WOMEN… no difference across groups.
How much genetic material is shared by DZ twins?
50% on average, but this varies from sibling to sibling
How can family resemblance studies measure hereditabilty of a trait?
If a trait is genetic, greater genetic similarity should equate to greater trait similarity.
What’s the problem with family resemblance studies?
In families, genetics are confounded by environment. Thus family resemblance studies tell us about upper limit of heritability.
How can adoption studies measure hereditabilty of a trait?
Compare correlation between parents and non-adopted children with correlation between parents and adopted children.
What are two problems with adoption studies?
- Selective placement – adoptive families are high-SES
2. Reasons for adoption – children may be disabled
How can twin studies measure hereditabilty of a trait?
Compare MZ and DZ twins in same/different families. If trait is genetic, MZ will be more similar than DZ twins.
What are two problems with twin studies?
- Assortative mating - people choose similar mates, thus DZ twins are more similar than chance
- Evocativeness - MZ twins are treated more similar than DZ twins - environmental factor.
Is the heritability for a given trait absolute?
No, it is a statistic for a given population at a given time.
On what two factors does heritability depend?
- The genetic variability of that population
2. The degree of variation in its environment
What two things can be done to change estimated heritability?
- Change variability in the environment
2. Change variability in genetic contribution
What effect would introducing a uniform schooling system have on heritability?
Reduce the variability of environment, and increase relative contribution of genetic influences: behaviours will appear more heritable. [basically, the more the environment resembles a lab, the greater the heritability estimate becomes]
What are Eric Turkheimer’s three laws of behaviour genetics?
- All (complex) human traits are heritable.
- The effect of being raised in the same family is smaller than the effect of the genes.
- A substantial portion of the variation in complex human behavioural traits is not accounted for by the effects of genes or families.
If a trait has _________ heritability it means that it is NOT greatly affected by existing ___________ ______________ experienced in that population.
If a trait has high heritability it means that it is NOT greatly affected by existing environmental differences experienced in that population.
What can population heritability estimates tell us about an individual case?
Not much. They’re an average.
Is environment or genetics the best predictor of number of fingers in humans?
Environment – because heritability coefficient is so low. h square = Gv/Pv
What can heritability estimates tell us about the consequences of new environmental manipulations?
Nothing.
What is the heritability formula?
h square = Gv/Pv
What does 1-h-square represent?
The combined effects of environmental and residual factors.
Two reasons why might twins separated at birth might share environments?
- In-utero conditions –twins share womb (dominant and submissive twin)
- Twins in Bouchard and McGue (1981) metaanalysis were separated at age 5.1 months on average
What happened to heritability of extraversion in a cohort born during WWII?
It decreased from .5 to .36. Relative contribution of environment has increased.
What are the current best estimates for genetic and environmental components of Big 5 in Western world?
Genetic – 50% Environment Shared – 30% Non-shared – 10% Residual –10%
