IQ is supposed to be a measure of intelligence and according to the theory we are born with a fixed amount of intelligence which cannot be increased by environment. However the original IQ tests were based on how well people responded to knowledge based questions, (e.g. they would need to have read popular books of the time to know the answers) which gave an advantage to people who lived in the same type of society as those who created the tests i.e. white western middle to upper class society. Modern IQ tests try to be more global and to be unbiased in that they avoid asking questions based on knowledge only available to some people. However even these IQ tests are flawed because as a measure of their accuracy they were designed to produce the same results as the earlier types. So for example a person who scored high on the original tests had to score high on the newer types for them to be considered accurate.
So to answer your question the type of environment a person is raised in can influence their IQ scores. For example if a child is raised in an environment which challenges them to remember, work out problems, where they are spoken to a lot by adults preferrably not using baby talk, where they read a lot etc. they will develop the skills necessary to increase their IQ. Adults can increase their performance in IQ tests also. There are books on how to e.g. http://www.amazon.com/IQ-Booster-Improve-Performance-Dramatically/dp/0806994223
However do not mistake IQ scores with intelligence levels. Some people can score highly in one area of IQ tests and score low in other areas giving them a low average. Some people who score high average IQ scores do poor in school examinations while others with low IQ scores do well. Do not get caught up too much in worrying about IQ scores. More important is having a well balanced happy child which is more likely to result in a successful adult.