Nature-Nurture Methods

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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 at. (1988)

Plomin et at. (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.