Teach your children how to be unbiased, so they can grow up to be good human beings capable of making sound judgments.
Children, at a very young age, are tempted to discriminate against other children different from them, and this tendency gets magnified when they enter their teens. Teenagers, often owing to peer pressure, are easily prejudiced against classmates at the slightest pretext. This kind of behavior can be self-destructive for your child in the long run, because making wrong judgments about people based on prejudices can impair his ability to make the right decision as an adult. He may choose the wrong person to enter into partnership with, to hire, to fire, to work for, to work with and, to marry. In addition, people with strong prejudices are rarely able to look inwards to see whether the fault lies within them, and if they can do something to remedy their troubles. They often blame others for their own problems
Here's how you can help your child grow into a balanced, non-prejudicial adult capable of making sound judgments.
Children often take their cues from their parent's behaviour, so if you ever see yourself making fun of a relative or speaking badly behind someone's back, stop yourself. Teaching your child to hate your relatives will achieve nothing.
Don't dwell on others' mistakes. You can discuss them once to give your child an example of wrong behaviour, but don't discuss them over and over again.
Turn inwards and take a look at your own prejudices. Are you prejudiced against a particular religion, community, class, caste of race? If yes, don't discuss your prejudices with your children. Even if your child may form his own opinions at a later stage and be more tolerant of other cultures than you are, he may develop prejudices in another form.
Don't generalize critisism. If someone has upset you, don't make sweeping statements like: "These Hindus/Muslims/Sikhs/Christians/Parsis etc are all the same/cannot be trusted."
Picture this. You go to a restaurant with your children and see a really fat person seated next to you. You point him out to your children, and all of you have a hearty laugh at that person's expense. What kind of message are you sending your children? That it is alright to discriminate or to make fun of someone based on their physical appearance. Instead, use the same situation as an example of how eating the wrong foods can lead to obesity, and which can lead to further health problems. Also, you can explain to your children how some people have health disorders that cause them to gain weight, and how others have eating disorders like anorexia. Ask your child if there are any fat children in his class, and if he makes fun of them. Discourage your child from such behavior, and at every step encourage your child to put himself in another person's shoes and see how it feels.
This way you can help your child gain an understanding of a subject, have an intelligent discussion and learn something new.
Praise the goodness in people every chance you get. This will teach your child to develop a more positive attitude, and be more optimistic in general.