Behavioral Genetics Practice Q's

If MZ twins are treated more similarly than DZ twins and this similar treatment affects the twin correlations, how might this bias our estimates of genetic and environmental influences?

The estimate of genetic influences may be too low

The overall variance of the phenotype will be wrong, so all our estimates will be off.

The estimate of genetic influences may be too high

The estimate of genetic influences may be too high

Which of these factors does not provide evidence that the disorder may have a genetic cause?

An increased frequency of the disorder in genetic relatives of an affected individual than in the general population.

A higher concordance in MZ twins than in DZ twins.

Individuals that live with an affected individual are more likely to also exhibit the disorder.

None of these indicate a genetic cause.

All of these indicate a genetic cause.

Individuals that live with an affected individual are more likely to also exhibit the disorder.

Studies testing the equal environments assumption have concluded that its violation is a major source of bias in conclusions about heritability.

True

False

False

A genetic correlation is when two phenotypes or disorders share the same genetic risk factors.

True

False

True

A genetic correlation (rA) < 1.0 for two traits indicates that there are some genetic influences that are unique to at least one of the traits.

True

False

True

A genetic correlation (rA) = 1.0 for two traits indicates that all the genetic influences on one trait also influence the other trait.

True

False

True

A twin study of attention problems finds rMZ = .75 and rDZ = .40 What is the heritability (a2)?

.70

There is not enough information to compute it.

.25

.05

.75

.7

A study of agreeableness finds rMZa (MZ twins reared apart) = .30. What is the influence of shared rearing environment (c2)?

There is not enough information to compute it.

.70

.60

.15

.30

There is not enough information to compute it

An adoption study of screen time finds rAS (Adoptive siblings) = .20 What is heritability (a2)?

.40

There is not enough information to compute it.

.00

.20

.80

There is not enough information to compute it.

Indicate which equation equals the correlation: DZ twins reared apart

rDZa =

C2

a2 + c2

0.5*a2 + c2

0.5*a2

a2

0.5*a2

Indicate which equation equals the correlation: MZ twins reared apart rMZa =

a2 + c2 + e2

C2

a2 + c2

0.5*a2 + c2

a2

a2

Considering general trends across twin studies, which of the following statements is true (select all that are true)?

When c2 is present, it tends to be in adulthood.

Shared environment (c2) seems to be more important than nonshared environment (e2)

Nonshared environment (e2) seems to be more important than shared environment (c2)

When c2 is present, it tends to be early in life

Nonshared environment (e2) seems to be more important than shared environment (c2)

When c2 is present, it tends to be early in life

If a child has a genetic predisposition towards aggressive behavior and tends to start fights with their classmates, the fact that other students are more likely to respond aggressively to this child compared to a timid child would be an example of:

GxE

evocative rGE

active rGE

passiverGE

evocative rGE

In order to develop some disorders, a person require both a diathesis (genetic propensity) and a stress (an environmental exposure). The diathesis itself it not sufficient to develop the disorder. This is an example of

GXE

active rGE

evocative rGE

passive rGE

GXE

Twins who share a single chorion must be:

monozygotic

dizygotic

monozygotic

If biological sibling pairs have more correlated SAT scores compared to adoptive sibling pairs, on average, this would be evidence that:

there are shared environmental influences that affect SAT performance

there are additive genetic influences that affect SAT performance

there are no additive genetic influences that affect SAT performance

there are additive genetic influences that affect SAT performance

A study of middle-school twins finds that performance on both math and vocabulary tests is heritable, but the heritability of math performance is higher than the heritability of vocabulary performance. Which of the following statements would be supported by these results (select all that apply)?

Teaching kids vocabulary is likely to be less successful than teaching them math.

Teaching kids math is likely to be less successful than teaching them vocabulary.

Some of the variation in both math and vocabulary performance is attributable to genetic variation.

Because they have different heritabilities, the genetic correlation between math and vocabulary must be small.

Some of the variation in both math and vocabulary performance is attributable to genetic variation.

A genetic correlation (rA) = 1.0 for two traits indicates that all the genetic influences on one trait also influence the other trait.

True

False

True

Which of the following statements regarding heritability is NOT true?

Heritability estimates are only applicable to the particular group, time, and circumstances for which it was calculated.

Heritability is a fixed property of a trait.

Statements about the heritability of individual differences should only be applied to a population, not an individual.

Heritability is a fixed property of a trait.

A twin study of attention problems finds rMZ = .75 and rDZ = .40 What is the heritability (a2)?

.70

.75

.25

There is not enough information to compute it.

.05

.7 2(rMZ - rDZ)

A twin study of introversion finds rMZ = .48 and rDZ = .24

What is the heritability (a2)?

.48

.24

.52

.00

There is not enough information to compute it.

.48

Indicate which equation equals the correlation: Biological siblings reared apart rBSa =

a2 + c2

C2

A2

0.5*a2

0.5*a2 + c2

.5*a²

If a child has a genetic predisposition towards aggressive behavior and tends to start fights with their classmates, the fact that other students are more likely to respond aggressively to this child compared to a timid child would be an example of:

GxE

evocative rGE

active rGE

passiverGE

evocative

The heritability of ADHD is highest when the students are in a disorganized classroom setting

A. rGE

B. GxE

GxE

Children with a genetic risk for ADHD are more likely to elicit a negative response from elementary school teachers

A. rGE

B. GxE

rGE (genetic code influences enviorment they experience)

Heritability of the environment indicates what form of rGE?

A. passive rGE

B. evocative rGE

C. Active rGE

D. Can’t tell

Cant tell- friends could seek you or you could seek them

What pattern of results indicates there are shared (C) environmental influences on a behavior?

MZt correlation > DZt correlation

MZt correlation and DZt correlation are similar and > 0

MZt correlation < 1.0

Adoptive sibling correlation > 0

B and D

B and D

What pattern of results indicates there are nonshared (E) environmental influences on a behavior?

MZt correlation > DZt correlation

MZt correlation and DZt correlation are similar and > 0

MZt correlation < 1.0

Biological sibling raised apart correlation > 0

B and D

MzT correlation <1.0

The shared environment tends to be the largest estimate in a twin model

True

False

False- smallest

___ enviornmental factors make family members similar

Shared

____ enviornmental factors make family members dissimilar

Nonshared

What does MZt correlation > DZt correlation imply?

Indicates genetics

What does MZt correlation and DZt correlation are similar and >0 imply

Home enviornment involved

Life course persistent

Smaller group, more heritable, barely due to enviornment

Adolescence- limited

Larger groip, less heritable, more enviornmental influences

Why might E be too large

Sometimes due to error or if children respond differently in shared experiences