Genetics Chapter 6
Genotypes- The way our genes interact to affect our personalities
Behavioural Genetics- The study of genetic and environmental contributions to individual differences in
personality and behaviour.
Genotype environmental correlation- What if people change environment and environment change
Phenotype- genotype + environment + gene-environmental correlation + gene-environmental
Heritability- The amount of observed individual differences in some characteristic that can be
accounted for genetic differences. It describes the difference among populations. Estimates for ethnic
groups because it varies across ethnic groups.
Environmentality- Estimates the extent to which observed individual differences can be traced in
anyway to individual differences in environments
Environmentality, heritability and measurement error account for all the characteristics of people.
Heritability for height is very good to judge in developed countries because their environment is the
same and people usually consume around the same amount of nutrition
Shared environment- Aspects of family environment that are usually the same for all children living in
Nonshared environment- Experiences that relatives have that make them different from each other.
Children growing up in the same family are no more alike than those growing up in different families.
MZA twins- Identical twins that are raised apart, this is good to tell if there is a difference between
heritability and environmental components
The double the difference method- Assumes that twins were reared under the same environment.
Assumption of representativeness, twins re not representative of the population when it comes to birth
rate and prematurity because they tend to weigh less and they are infrequently born.
Equal environments assumption- Pertains to similar treatment that is needed for the specific study.
The rmza method- Researchers assume that adopted families of each twin are different from each
Selective placement- When the adopted families of each twin are similar it makes it impossible to see
the effects of genetics apart from environment because it joins the two. Mza studies with adopted families- They usually assume that adopted families are like non adoptive
families but these types of