The role of environmental factors on intelligence as a whole has been supported by many findings and theories however as intelligence is a complex thing other factors such as genes have to be considered when trying to define exactly how much of a role environment has on intelligence. Pinning it down to one factor only will get psychologist accused of being reductionist or deterministic which may de-value their work.

Most of the conclusions made by sociologists and certain psychologists seem to indicate that nurture has a massive impact on our IQ when they haven’t considered the role of genes. Studies done on twines, different family types and adoption seem to indicate a role for genes, leaving us to conclude that some environmental factors effecting genes may actually be the result of our underlying biology. For example an adoption study which looked at the correlation of IQ scores between biological parents and the child that’s been adopted showed that the average correlation was 0.48 compared to 0.19 for child and adoptive parents. This shows us that even though children are sharing the same environment as their adoptive parents their IQ scores correlate higher with the biological parents meaning genes have more of an impact on IQ scores (Munsinger 1975).

In addition to this several studies done by Plomin revealed that as a child grows older their IQ correlates weaker with their adoptive siblings and stronger with their biological parents. This can be explained by niche picking.It’s when a person’s likes and dislikes are influenced by their genes and so as we get older we have more control over what environments we want to spend time in which influences our intelligence. Here is an example of how this may work in real life. So, for example a person is born with a shy temperament which will influence what kind of environment they choose for themselves and then that environment will alter how their IQ score. A shy person is likely to choose places that are quiet where they can go unnoticed like a library which leads them to going there more often and reading more. As a result of reading more they improve their vocabulary which puts them at an advantage on one part of the IQ test. Therefor they’re seen as more intelligent.

Adoption studies are very helpful in showing how genes influence intelligence because without them we wouldn’t be able to see how having almost the same type of genes influence a person’s IQ because they’d most likely be sharing the same environment. However when children are adopted they are done so by selective placements. This is where their adoptive families are closely matched with the child’s biological parents based on social economic status, religion and various other things. Perhaps this means that the adopted children’s IQ is not completely down to genes when they’re put in an environment that more or less resembles that of their biological parents. Nevertheless effects of genes can still be seen because if IQ score was down to just environment then correlations would be higher between adoptive parents and child because they’re sharing the exact environment rather than one that resembles each other.
A study done by Capron and Duyne (1989) removed the problem of selective placements because they compared children going from a high SES to low SES and low SES to high SES. Results showed that the SES of the biological and of the adoptive parent had about the same effect meaning both nature and nurture are as important as each other. This view is not looked at by naturists or naturists.
Both argue that their side is the one that explains the whole outcome of intelligence which leads them to being too deterministic. The naturists say that the IQ score is completely down to gene and any factors that seem like they are as a result of the environment is probably an indirect effect of genes. This is a problem because it doesn’t allow explanations for other factors that in reality may be having a massive effect on intelligence. Similarly the naturist’s are as deterministic as the naturists. They argue that intelligence is down to our environment only and any other factors mentioned are disregarded. Being deterministic is bad for both sides because it leads to them being reductionist as they are reducing a highly complicated matter to being as a result of one factor which is probably false as it is an interaction between the two. A good way to see how the two interact is by looking at reaction range.

Gottesman (1963) talks about how our genes sets us a development potential but it’s our environment which has an impact on exactly how much of that potential we fulfil. For example someone may have low potential but living in a good environment that allows them to have a good diet and enriched surroundings allows them to reach the top of their potential, similarly someone may have high potential but living in a bad environment leads them to reach the minimum of their potential. This means that both our genes and environment play an important role in defining our IQ score.

Culture has an impact on a person’s IQ and is considered as part of an environmental effect because it is a number of behaviours, which genes have little or no control over, that is shared by a group of people. There is obvious differences between cultures when comes to IQ, though many would question the ability of one test to measure IQ’s of many different peoples. This is because different people put different amounts of emphasis on certain skills or use a different type of logic to the western one which IQ tests are based on. For example the Canal children who were considered as lazy and stupid had the average IQ score of 60, but it’s argued that this score actually reflected the impatience of these children, their familiarity with mainstream culture and their willingness to answer questions which they thought to be irrelevant. These points made make it hard to accept the score point of 60 is an accurate measurement of their IQ rather than their patience. Some psychologist go as far as to say the tests came nowhere near to measuring these children’s intellectual ability which leads us to question the validity of the methods used to measure intelligence.

Methodological problems are clear when it comes to measuring the role of environment and genes on intelligence especially when it comes to measuring effects of culture. When IQ tests have been used in a variety of different cultures there has been a wide range of results which indicates differences in cultures however these differences are so big and at times offensive that it leads us to question the validity of these tests. A test designed to measure intellectual abilities of a western culture which puts importance on specific skills such as working fast will probably not be a good method of measuring intelligence in a culture where people have no care for how fast a person can complete a task. This was demonstrated by Yakima Native Americans when they given the task of placing different shaped wooden blocks into the appropriate hole as quickly as possible by Kleinberg (1971). It was found that children of that culture had no problem with completing the task but as they failed to finish on time their score was lowered. From this we can see the problems with using an IQ test that has been standardised in a western culture on western people.

An interesting phenomena is the black-white achievement gap. This gap seems to show how bad an effect cultural/home life can have on how well a child can do in school and on an IQ test. An example of the explanation for this gap is the use of AAVE by African American people. This basically indicates that because they speak differently they are at a disadvantage when it comes to written tests, however when questions that relied on such abilities were translated into black dialect little or no difference was shown in their IQ score (Quay 1917) .This is an interesting finding which suggests maybe it’s not the environment they live in or the way they’re taught to speak which has an effect on IQ and maybe black peoples ‘intelligence genes’ are different compared to the whites or the Ashkenazi Jews. Nevertheless other environmental factors such as living in poverty may. Perhaps it’s just school and parents failing to give the children the best opportunity in life.

As with many factors in intelligence the Middle Eastern average IQ score which is between 82-86, shows signs of both nature and nurture having an influence on intelligence. This is because of the fact that 20- 50% of marriages are between cousins in the Middle East whereas only 1% of marriages are between cousins in Europe. This show us that genes defiantly have a role on intelligence even if it may be indirect. ( The problem with pinning down intelligence to one variable is that you’re most probably wrong because the outcome of your IQ test is down the skills you have which you could have either learnt or inherited.
Overall the role of environment on intelligence is big because to a certain extent it’s the environment which influences how much exposure people have to different skills which makes a person be considered as ‘intelligent’. If a person hasn’t had the chance to practice these skills and become good at it then they’ll be considered as ‘dim’. So we can’t judge exactly how intelligent people are when some have environmental advantages. However environment is not the only thing determining what a person’s IQ will be. We must consider other variable such as genes. Even though there not an intelligence gene some people just seem to be smarter. This may be demonstrated when looking at differences within a group. Even though they’ve all had the same environment throughout their life there are still difference between them which can be down to genes. Some people are just faster than others at picking up certain skills or understanding concepts which makes them more intelligent than the rest. Again it’s hard to define exactly what intelligence is down to but environment has a role. How big that role is still being debated.