Heritability

what is heritability?

the proportion of total variation in. a trait associated with genetic variation

what does heritability range from?

0 to 1, or 0% to 100%

what does high heritability mean?

more of the trait variation in that population is associated with genetic variation

what does low heritability mean?

less of the trait variation is associated with genetic variation

is heritability a universal law?

no, it is an estimate and depends on context, sample, population or environments

why must heritability be interpreted carefully?

a score from one group may not apply may not apply to other populations or environments

why are twin studies important historically?

they compared monozygotic and dizygotic twins to estimate genetic influence

what are monozygotic twins?

twins from one zygote; genetically very similar

what are dizygotic twins?

twins from two zygotes; less genetically similar

why are monozygotic twins usually more similar than dizygotic twins?

greater genetic similarity is associated with greater trait similarity

are monozygotic twin correlations ever 1.0?

no, they are higher than chance but not perfect

what issue exists with older twin-study heritability estimates?

they often produced higher estimates because of assumptions and weaker controls

what are modern heritability estimates often like for psychological traits?

non-zero but lower, often around 0.1 to 0.3 depending on the trait

what example does the prof give for IQ?

twin-study estimates may be around 0.8 in adults, but modern genetic methods may estimate closer to 0.3

if heritability is 0.3, does that mean environment explains 0.7?

not necessarily; the rest may include environment, error, chance, and unexplained factors