1. Nature VS Nurture
intelligence

2. Genetics:
As you know, we have genes which give us different characteristics and these genes are inherited from our parents. The actual genetic code is known as the genotype. However, you get one gene from each parent for everything, but obviously only one of these can be expressed; so how the genes actually manifest themselves is called the phenotype.

3. Types of studies :

4. 1) Twin Studies:
dizygotic
monozygotic

5. Shields (1962),
Looked at MZ twins (since there genetics are the same) who have been raised together or apart.
found the correlation between intelligences of MZ growing up together was 0.83 and growing up apart was This would appear to show the environment is more important.
it is only recently that we can prove two twins are identical, it could be that DZ twins that looked very similar were included because they thought they were identical.
there is the issue of what was counted as 'separated' in the study, some twins were included who were raised but different family members but lived near to each other, regularly saw each other and went to the same school.

6. 2) Adoption Studies
Adoption studies involve looking at someone who has been adopted and comparing their intelligence with their biological and adoptive parents.
If the IQ was more similar to their biological parents who have DNA in common, then we could conclude intelligence was as a result of nature.
if the IQ was more similar to the adoptive parents who have the upbringing in common, it would be nurture.
Evaluation of these studies: *The matching of parents. The authorities tend to find adoptive parents who are similar to the biological so the transition is easier for the child. For example, matching up parental occupations. *Small samples; it is difficult to find people willing to come forward who also know their biological parents, this makes the results less representative.

7. 3) Selective Breeding Studies:
involve breeding intelligent parents to see if the offspring are intelligence.
Because of ethical reasons such studies cannot be carried out on humans. But in 1940, Tyron conducted a selective breeding study on rats.

8. Intelligence is a heritable characteristic in rats.
Aim:
Use selective breeding in rats to see how genetics influences intelligence.
Method
A large number of rats were trained to run a maze. It was then recorded how many errors each made. The best rats at the task were called maze bright and put together and the rats poor at the maze were maze dull and they were also put together to breed
Conclusion
Intelligence is a heritable characteristic in rats.
Evaluation
The positives of this type of study are that rats have a rapid life cycle so many generations will be produced in a relatively short time and that the vast majority of DNA in rats and humans are the same. However the big weakness is that it doesn't very well relate to humans, since maze solving does not equate to human intelligence and that breeding within a family (as the rats did) is known to very often cause genetic problems that can severely impair intelligence

9. Conclusion For all studies:
Both nature and nurture play an important role, however perhaps that the environment is the deciding factor.
The idea used to describe it is the Rubber Band Hypothesis. It says that the potential (length of the band) is decided by genetics. However the environment stretches this band, so that someone with a low potential could be stretched beyond someone with a high because of environmental differences. However if someone with a high and someone with a lower genetic potential had the same environment, that person with the higher genetic potential would be able to 'stretch' their intelligence to a higher level.