Nature-Nurture Methods
Psychology: AQA A Level, topic 8.1.12
Methods of Studying Nature-Nurture Influences
There are three different varieties of methods that study the effect of nature versus nurture. These are family studies, adoption studies and twin studies.
Family studies
- Family studies, like the name suggests, looks at families.
- Biologically related families will share genetic information
- Traits are more likely to be shared within families. So family studies are useful when studying genetic influence.
Family studies - limitations
- But families are also likely to share the same environment.
- So family could also be an environmental influence because people learn behaviours from those around them.
- For example, children learning behaviours from their parents.
Adoption studies
- Adoption studies are another form of method to study nurture-nature influence.
- In these studies, adopted children are compared to their biological parents and to their adoptive parents.
- In so doing, researchers can determine which traits are of genetic influence (nature/biological) and which are of environmental influence (nurture).
Adoption studies cont.
- The child will share genetic traits with their biological parents and share the same environment as their adoptive parents.
- So if they have similarities with their biological parents, then nature is important.
Evidence - Plomin et al. (1988)
- Plomin et al. (1988) conducted a study and found that there was a stronger correlation of IQ with biological families than with adoptive families.
- So it is possible to argue that nature is more important than nurture in the development of intelligence.
Methods of Studying Nature-Nurture Influences
There are three different varieties of methods that study the effect of nature versus nurture. These are family studies, adoption studies and twin studies.
Twin studies
- The final method of studying nature-nurture influences is twin studies.
- There are two main types of twins: monozygotic and dizygotic.
- Monozygotic twins share 100% of their genetic information as they develop from the same egg (single egg = monozygotic).
- Dizygotic twins only share 50% of their genes, the same as non-twin siblings. They develop from two separate fertilised eggs (two eggs = dizygotic).
Usefulness of twin studies
- Twins are useful in studying nature/nurture as researchers can identify behaviours/traits/characteristics that are due to genetic influence more explicitly.
- Concordance rates can also be determined.
- Concordance is how likely one person is to have a specific trait based on the fact that another person does.
Holland et al. (1988)
- Holland et al. (1988) surveyed anorexia rates.
- They found that monozygotic twins had 56% concordance rates.
- There was only a 5% concordance rate amongst dizygotic twins (if one twin had anorexia, then 5% of the time both twins did).
- Holland suggested that this showed that anorexia has a genetic component.
Holland et al. (1988) cont.
- But if it was truly due to genetics, there would be a 100% concordance rate.
- So because they did not find this, there must be some environmental influence.
- It could be that identical (monozygotic twins) are treated more similarly (stronger environmental influence).
Environment
- It would be beneficial to study monozygotic twins raised in separate environments to be truly accurate in eliminating traits due to genetics.
- Obviously, this is rare and difficult to do.
Test yourself on Nature-Nurture Methods
What are the three ways of studying nature and nurture influence?
What are concordance rates?