Discuss How We Study Heritability

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--Behaviour genetic designs allow us to estimate the heritability of traits and diseases.By heritability,we mean the extent to which genes contribute to differences in a trait among individuals.Some traits,like height,are highly heritable.In contrast,other traits,like the accent in our speech,are due almost entirely to environment.That's because our accents are almost entirely a product of the dialect spoken in the community in which we're raised.
--Heritability isn't as simple a concept as it seems,and it confuses even some psychologists.The first misconception is that heritability applies to a single individual rather than differences among individuals.That's because heritability is a statistic that applies only to groups of people.Heritability tells us about the causes of differences among people,not within a person.A second misconception is that heritability tells us whether a trait can be changed.Many laypeople believe that if a trait is highly heritable,then by definition we can't change it.Yet,logically speaking,heritability says little or nothing about how malleable or alterable a trait is.In fact,a trait can,in principle,have a heritability of 100 percent,yet still be extremely malleable.
--Scientists estimate heritability by means of one of three behavioural genetic designs: family studies,twin studies,and adoption studies.In such studies,scientists note the presence or absence of a behavioural trait or a psychological disorder among different relatives.These studies determine how much genetics contributes to the expression of that trait or disorder.In a family study,researchers examine the extent to which a trait "runs" or goes together in intact families,those in which all family members are raised in the same home.We can study correlations in a trait between two types of twins.Consequently,if identical twins are more alike on a psychological characteristic,such as intelligence or extraversion,than are fraternal twins,we can infer that this characteristic is genetically influenced.Nevertheless,twin studies hinge on the "equal environments assumption"-the assumption that the environmental influences on the characteristic we're studying are the same on identical as on fraternal twins.Adoption studies,which examine the extent to which children adopted into new homes resemble their adoptive as opposed biological parents.Children adopted into other homes are genetically similar to their biological relatives,but they don't share the same environment with their biological relatives.As a consequence,if adopted children resemble their biological parents on a psychological characteristic,we can typically assume that it's genetically influenced.

Discuss How We Study Heritability

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