There have been many novels written about the changes in a person's character resulting from a change of environment. The best example is probably Joseph Conrad's Heart of Darkness. Others that come to mind are Mark Twain's The Prince and the Pauper and Daniel Defoe's Robinson Crusoe. Charles Dickens' famous novel Oliver Twist emphasizes the effect of environment on children. An excellent movie that deals with the effect of environment on a character is Dances with Wolves, in which the young soldier isolated in Indian territory gradually becomes an Indian ("turns Injun") himself. An classic black and white movie that focuses on the effect of environment on young people is Dead End (1937), featuring Humphrey Bogart and the Dead End Kids.
A person’s environment affects the way they live and think because it strongly affects what influences they are exposed to and what opportunities they have.
For example, if a person grows up with parents who do not have much formal education, they may not come to think that education is important. They may be influenced by their parents to think that it is normal to drop out of school and go to work. This will affect their attitude towards school and may make them look unintelligent and unmotivated. If they do end up dropping out of school, they will typically have much less in the way of opportunities than someone raised in an educated family.
The way of thinking and the lifestyle of people is greatly influenced by the environment. The people are forced to think according to the environment. If the society one lives in has a high stardard of living, the person is forced to have his high standard of living or else he might be disregarded in the society. It is necessary to cope and adjust in the society, so similar thinking is essential.