22 Behaviour, Genetics and Personality: from Galton to Bouchard

Question 1

When did Sir Francis Galton publish Hereditary Genius?

Answer 1

In 1869

Question 2

What were Galton’s findings and conclusions in Hereditary Genius?

Answer 2

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

Question 3

Who invented the term “Eugenics”

Answer 3

Sir Francis Galton

Question 4

What did Thornhill and Palmer (2000) argue about rape?

Answer 4

That raping women may be an adaptation.

Question 5

What did Dar-Nimrod find to be the effect on view of rapists when Pps exposed to the evolutionary argument for rape?

Answer 5

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.

Question 6

How much genetic material is shared by DZ twins?

Answer 6

50% on average, but this varies from sibling to sibling

Question 7

How can family resemblance studies measure hereditabilty of a trait?

Answer 7

If a trait is genetic, greater genetic similarity should equate to greater trait similarity.

Question 8

What’s the problem with family resemblance studies?

Answer 8

In families, genetics are confounded by environment. Thus family resemblance studies tell us about upper limit of heritability.

Question 9

How can adoption studies measure hereditabilty of a trait?

Answer 9

Compare correlation between parents and non-adopted children with correlation between parents and adopted children.

Question 10

What are two problems with adoption studies?

Answer 10

1. Selective placement – adoptive families are high-SES

2. Reasons for adoption – children may be disabled

Question 11

How can twin studies measure hereditabilty of a trait?

Answer 11

Compare MZ and DZ twins in same/different families. If trait is genetic, MZ will be more similar than DZ twins.

Question 12

What are two problems with twin studies?

Answer 12

1. Assortative mating - people choose similar mates, thus DZ twins are more similar than chance
2. Evocativeness - MZ twins are treated more similar than DZ twins - environmental factor.

Question 13

Is the heritability for a given trait absolute?

Answer 13

No, it is a statistic for a given population at a given time.

Question 14

On what two factors does heritability depend?

Answer 14

1. The genetic variability of that population

2. The degree of variation in its environment

Question 15

What two things can be done to change estimated heritability?

Answer 15

1. Change variability in the environment

2. Change variability in genetic contribution

Question 16

What effect would introducing a uniform schooling system have on heritability?

Answer 16

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]

Question 17

What are Eric Turkheimer’s three laws of behaviour genetics?

Answer 17

1. All (complex) human traits are heritable.
2. The effect of being raised in the same family is smaller than the effect of the genes.
3. A substantial portion of the variation in complex human behavioural traits is not accounted for by the effects of genes or families.

Question 18

If a trait has _________ heritability it means that it is NOT greatly affected by existing ___________ ______________ experienced in that population.

Answer 18

If a trait has high heritability it means that it is NOT greatly affected by existing environmental differences experienced in that population.

Question 19

What can population heritability estimates tell us about an individual case?

Answer 19

Not much. They’re an average.

Question 20

Is environment or genetics the best predictor of number of fingers in humans?

Answer 20

Environment – because heritability coefficient is so low. h square = Gv/Pv

Question 21

What can heritability estimates tell us about the consequences of new environmental manipulations?

Answer 21

Nothing.

Question 22

What is the heritability formula?

Answer 22

h square = Gv/Pv

Question 23

What does 1-h-square represent?

Answer 23

The combined effects of environmental and residual factors.

Question 24

Two reasons why might twins separated at birth might share environments?

Answer 24

1. In-utero conditions –twins share womb (dominant and submissive twin)
2. Twins in Bouchard and McGue (1981) metaanalysis were separated at age 5.1 months on average

Question 25

What happened to heritability of extraversion in a cohort born during WWII?

Answer 25

It decreased from .5 to .36. Relative contribution of environment has increased.

Question 26

What are the current best estimates for genetic and environmental components of Big 5 in Western world?

Answer 26

Genetic – 50%
Environment
Shared – 30%
Non-shared – 10%
Residual –10%