genetics Flashcards by Taylor Dunn

explain personality is like lemonade analogy

water, lemon, sugar are all different ingredients

but when combined it creates something fundamentally different than the start and you cannot separate ingredients
this is similar to environment and genetics

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because environment and genetics go hand in hand what does this mean

taking sides in nature v. nurture debate is nonsensible

nature = genes biology and brain
nurture = environment

so it is nature and nurture, rather nature by nurture
-they interact with each other and affect each other

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what is trait genotype

genetic code carried in DNA, blueprint

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what is trait phenotype

physical expression, observable

genotype can affect phenotype
phenotype is also influenced by the environment

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example of genotype and phenotype in animal world

ex. pinkness in flamingos depends on the environment

ex. genotype of cats can affect the shape of their ears

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so, overall differences of genotype and phenotype

genotype: genetic makeup, determined by observing DNA, depends on genes, inherited by offspring, consists of expressed and suppressed genes
phenotype: observable characteristics, depends on genotype and environment, not inherited, and consists of just expressed genes

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explain the differences between heritable and genetically determined

heritable: the extend to which genes explain differences between people on a trait
genetically determined: genes cause a characteristic

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explain number of fingers and toes example

genetically determined but heritability is low (because that is about explaining differences)
-when there are differences, they are not explained genetically, very rare for genetics to cause this usually caused by environment

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what does heritability (h^2) tell us

genetically determines variation / total amount of variation

ranges from 0 to 1 like a correlation
the closer to 1 means more variation explained by genetics

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explain heritability example in plants

plants with 100% heritability with different heights in the same environment, all the differences can be explained by genetics

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what does heritability (h^2) does not tell us

tells us nothing about individuals (need a group to explain differences)
nothing about the cause of a trait

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what is heritability in words

our genes explain 90% of differences in our heights
NOT
that genes determine 90% of height in individuals

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explain pierced ears example (0% genetically determined, 70% heritable). how is this possible?

our genes explain 70% of differences in having pierced ears

-differences in gender (XX, XY)

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what is heritability specific to

one population in one environment
-heritability estimates can change

ex. heritability of height across countries
US 80%, China 65%, Africa 65%, Aussie 87%
-heritability increases in access to food/healthcare
-if everyone comes from similar environment differences have to be explained by genetics so heritability will go up

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what is environmentality (e^2)

estimates extend to which individual differences can be traced to differences in the environment
-as heritability goes up environmentality goes down and vice versa

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explain identical twins and environmentality

identical twins share 100% of DNA but look slightly different because of environmentality

starts in womb
ex. touching different parts of amniotic sac for fingerprints

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what is shared enviroment

aspects of the family enviornment that are the same for children

ex. physically dwelling and aspects of it (# of books), SES, parenting style etc.

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what is nonshared environment

unique experiences in and outside of the family

ex. friend group, hobbies, birth order

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what are the two types of twins

monozygotic twins and dizygotic twins

difference between monozygotic twins and dizygotic twins

MZ: identical twins, share 100% of DNA, occur when egg splits in two
DZ: fraternal twins, share 50% of DNA like normal sibling pairs, two different eggs born at same time

what twin studies are done

twins reared (raised) together (MZ twins reared together and DZ twins reared together)
twins reared apart (MZA and DZA)

what adoption studies are done

twins reared apart
adoptive siblings (family just adopts 2 different siblings_
adoptive parents and children

genetics shared of:
 MZ twins reared together
DZ twins reared together
MZ twins reared apart
adoptive siblings

MZ twins reared together: 100% genes, 100% environment
DZ twins reared together: 50% genes, 100% environment
MZ twins reared apart: 100% genes, 0% environment
adoptive siblings: 0% genes, 100% environment

what can twin studies tell us

heritability and environmentality, the extent to which these play a role

explain Minnesota twin study

100 pairs of identical twins separated at birth | -found uncanny similarities between identical twins reared apart (in health, IQ, etc)

how is heritability measured in twin studies

- correlation between MZ twins reared apart | - correlation of MZ twins v. DZ twins

what are the four issues with twin studies

1) equal environment assumption 2) assumption of representativeness of twins 3) selective placement 4) assumption of representativeness of adoptive families

explain equal environment assumption

- comparing MZ to DZ twins - assume MZ twins are treated more similarly than DZ twins, to the extent MZ twins are treated the same it could inflate the correlation (environment causes it, not heritability)

explain assumption of representativeness of twins

might not be generalizable to population

explain selective placement

- how similar are adoptive families to one another | - twins reared apart might be similar because of similar environments

explain assumption of representativeness of adoptive families

how generalizable are adoptive families

explain heritability estimates of twins (extraversion and neuroticism)

as degree of relatedness increases, so does the correlation in personality traits - highest in twins reared together - correlations in identical twins reared apart get lower (so environment does matter) so, the more people are related to each other the stronger the similarities in personality

explain heritability of the 5 factor model

appears that traits are determined by heritability and environment about 50/50 -shared environment is very low in determining traits almost all individual differences (personality, psychopathology, and cognitive ability) in human behavior are moderately heritable

so what does observed differences in personality traits = ?

= 40% genetics + 40% non-shared environment + 0% shared environment + 20% error

what is genotype-environment interaction

people respond differently to environment because of their genetic makeup

explain the methods and variables in the genotype-environment interaction study with the serotonin transporter gene (Caspi et al)

the serotonin transporter gene is the gene that influences how much serotonin a person has method: tracked 1037 adults from 3years-26 years, looked at type of serotonin transporter gene predictor variables: 1) genotype of serotonin transporter gene - SS (short gene from both parents) - ll (long from both) - Sl * *S associated with decreased serotonin levels** 2) number of stressful life events (looked at major stressors) outcome variable: depression (level and number of episodes), suicide attempts, and suicide ideation

what are the results of the genotype-environment interaction study with the serotonin transporter gene (Caspi et al)

found same pattern in all variables of interest -as number of stressful life events increases the outcome variables increase (most for SS gene, least for Sl gene) -those with S genotype had double amount of depressive episodes than those with l genotype (both with 4+ stressful life events)

explain genotype-environment correlation and how it is different than the interaction

``` certain genotypes (G) tend to occur with certain environments (E) -know there is a relationship, but not clear cut ```

explain a positive genotype-environment correlation

1) G increases, E increases - as genetic predisposition increases, the demand from the environment increases ex. talkative person finds themselves in talkative job

explain a negative genotype-environment correlation

1) G increases, E decreases - as genetic predisposition increases, less likely to find themselves in environments ex. neurotic person, less likely to find themselves in anxiety producing situations

what are the three types of G-E correlations

passive, reactive and active

explain passive G-E correlation

parents own inherited traits cause both their child's G and E ex. parents good at verbal ability, pass on genetics and create verbal environment (positive example)

explain reactive G-E correlation

people treat child differently (E) based on the child's G | ex. child is verbal from genes, so people talk more to the child (positive)

explain active G-E correlation

a child's G leads him/her to seek out certain E | ex. talkative child seeking out the more talkative parent (positive)

what are epigenetics

the idea that environment can change genes | -what genes are and are not expressed