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Psychology and the Individual > topic 5- heritability > Flashcards

topic 5- heritability Flashcards

1
Q

what is heritability?

A

An estimate of the average proportion of variance in any behaviour thought to be accounted for by genetic factors across the population

aka how much phenotypic variance is attributable to genotypic variance

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2
Q

what is the additive assumption?

A

the assumption that argues there are only two components that determine phenotype:

  1. the genetic part
  2. the environment
    - these will always add up to 100% of variance in a phenotype
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3
Q

what is shared enviroment?

A
  • environmental variation which is shared with family members
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4
Q

what is an example of how heritability changes?

A
  • the heritability of height is increasing with each generation
  • this is because environmental influences are causing less variation as there is more equality in things such as nutrition and living conditions
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5
Q

what is the heritability formula?

A

H^2 = 2( rmz - rdz)

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6
Q

what is the concordance rates for IQ and how is this used to get a heritability estimate

A 
MZ = 86% concordance
DZ = 55% concordance

therefore there is a 0.62 heritability

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7
Q

what are examples of residual effects impacting concordance rates?

A

non shared enviroment, errors of measurement, developmental accidents, G x E interactions

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8
Q

What was Galtons observations of judges on the English bench

A
  • 286 judges were appointed to the english bench between 1660 and 1865
  • 109 had one or more relatives who were also ‘emminent’
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9
Q

What was Galtons adoption study?

A
  • He compared sons of emminent men with adopted sons
  • adopted sons were much less likely to achieve emminence than the natural sons were
  • “the social helps are the same but hereditary gifts are wanting”
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10
Q

who was the founding president of the British Eugenics society?

A

Galton

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11
Q

what is the heritability of each FFM trait?

A 
Extraversion- 56%
Neuroticism- 80%
Aggreableness- 46%
Contientiousness- 72%
Openness- 38%
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12
Q

what was Loehlin et al’s adoption study?

A
  • compared personality dimensions between adoptive children and their biological and adoptive parents
  • there was a stronger correlation between child and biological parent than there was child and adoptive parent
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13
Q

What was Pederson et als twi study?

A
  • studied twins reared together and twins reared apart
  • for extraversion, the concordence for identical twins reared apart was higher than the concordence for non identical twins reared together or apart.
    (further results in 5.4 lecture 2)
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14
Q

what is narrow heritability?

A
  • the fraction of the phenotype that is only due to additive genetic variance
  • additive genetic variance is the variance explained by the sum of different gene variations that are involved
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15
Q

what does broad heritability include?

A

additive genetic variance
dominant genetic variance
epistatic genetic variance

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16
Q

what is dominant genetic variance?

A

variance attributed to one gene that is dominant over another

17
Q

what is epistatic genetic variance?

A
  • genes interacting with each other
  • when one genetic variant interacts with another genetic variant to produce a larger effect that the sum of each individual effects would be
18
Q

what is the passive model of gene environment correlation?

A
  • behaviour in a child as a result of parent and child sharing the same genes
  • e.g child inherits the gene for shouting and is also in an environment where the parent is shouting. therefore both the genes and the environment promote shouting
19
Q

what is the child effects model of gene environment correlation?

A
  • gene causes behaviour in child which in turn causes the same or similar behaviour in the parent
  • e.g child inherits a gene for shouting and the child shouting causes the parent to shout
  • the parent shouting then causes the child to shout more
  • essentially the child has created an environment where their own natural behaviour is being intensified
20
Q

what is the parent effects model of gene environment correlation?

A
  • behaviour in the child is responded to by the parent which in turn brings out the behaviour in the child
  • the child doesnt inherit a natural tendency to shout
  • however if the child does shout this is responded to by the parent which further brings out this behaviour
21
Q

how may non-shared environments make twins seem more similar?

A
  • a parent may be doing a lot to influence one twin and not much to influence another to make the twins seem more similar
  • for example, if one child is naturally intelligent and the other not, a parent may leave the first child alone but do a lot to raise the intelligence of the second twin
22
Q

are heritability estimates normally higher in twin studies or adoption studies?

A

twin studies

23
Q

what did Karmin and Goldberger say about twin studies?

A
  • twin studies overestimate heritability

- this is because identical twins have more similar environments than fraternal twins

24
Q

why might twin studies be unrepresentative in terms of birth weight

A
  • twins are more likely to be premature and have low birth weight
  • lots of studies have linked prematurity and low birth rate as a risk factor for different neurodevelopmental conditions
25
Q

what does stoolmiller ague about the representivity of adoption studies?

A
  • placement strategies of adoption agencies influence heritability statistics
  • economic influence is often not explored
26
Q

describe assortive mating

A
  • for some traits similarity attracts, for other traits opposites attract
  • ginsburg and collegues found that body height is positively correlated between spouses
  • if parents are more similar to each other then children are likely to be more similar to each other. This would lower a heritability estimate
27
Q

what is the Wilson effect?

A
  • Heritability of IQ increases with age
  • monozygotic twins became increasingly concordant with age
  • dizygotic twins became increasingly less concordant with age
28
Q

Why might the Wilson effect be the case?

A
  • as a child and teenager environments such as school is more likely to be shared
  • as an adult a high IQ may lead someone to a very different environment than someone with a naturally low IQ
29
Q

What were Neisser and Colleagues 3 types of environmental influences on IQ?

A
  • biological variables and maternal effects
  • school and education
  • family environment
30
Q

What was benton and roberts findings in nutrition and IQ

A
  • children who were given vitamin and mineral supplements showed an increase in IQ scores
  • however third variables such as disposable income and caring attitudes may have been involved
31
Q

what two types of exposure to lead have both been linked to lower IQ scores?

A

pre-natal exposure to lead
and
childhood exposure to lead

32
Q

what did mortenson find about smoking and IQ?

A

women who smoked 20 or more cigarettes daily in late pregnancy were likely to have sons who performed less well on IQ tests

33
Q

what was Delvin’s finding about prenatal conditions and twins

A

prenatal conditions account for 20% of the variance in the IQ of twins

34
Q

what did Neisser and collegues say about school and IQ?

A
  • going to school is likely to increase your abilities, especially those relating to intelligence, so intelligence acts as a dependent variable
  • intelligence is likely to influence your attendence at school and your length of schooling, so intelligence also acts as an independent variable
35
Q

what was Newcombes summer camp study?

A
  • newcombe argued that there is a low correlation between extraversion and behaviour (r= 0.14)
36
Q

what was epsteins counterargument to Mischel?

A
  • personality researchers have not measured the relationship between traits and behaviours correctly
  • when corrected for situational factors, the correlation between personality and behaviour may be as high as R= 0.52
37
Q

what was Gollust and collegues opinions on genetic testing?

A

asked 900+ participants who had taken such tests their opinions

80% of people said they should have a right to access genetic testing information directly, that parents should be able to get genetic testing information for their children and that results should be kept private

Psychology and the Individual (6 decks)

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