Prejudice people evolve due to parental upbringing not social influence.
Firstly, many people think that prejudice is caused by a mixture of what our parents teach us, what the media shows us, and our own personal experiences involving a person of a different race.
Secondly ,Some people think the causes of Prejudice is when someone simply hates how one or a group of people act, speak, dress, and then they go ahead and hate the whole race which is not fair.
Thirdly, others believe that prejudice is nothing more than a strong dislike of character or personality. Not every individual of any one group acts the same, but it’s the actions of the majority that set the "standard" for how a group will be viewed. Take music for example. Heavy metal lovers are said to be druggies, but not all of them are. Rap lovers are said to be violent, but not all of them are. Yet it's hard to go to a rap concert without thinking about a gun fight.
Fourthly, various people believe that people in general have a tendency to think that they are right. What they think, eat, read, like or dislike. Therefore any opposition to that is wrong. To think that the opposition is wrong is prejudging, forming an opinion without all the facts. We all do it to some degree or another that is just human nature
Lastly, many believe that the way one is raised (no matter what your ethnic-background; European, African, Hispanic, etc), can contribute to developing prejudice attitudes. Lack of interaction among people of different backgrounds can contribute to misconceptions about others and therefore, prejudiced attitudes. Mistreatment by another group of people (different ethnic-backgrounds, different income-levels, different religions, etc), will certainly cause the individual being mistreated to develop a negative attitude towards that group of people who are abusing them.