Kids are not born to be prejudice. It is something that they learn over time and much of it depends on who their friends are, and how they are raised in a family.
Parents who want to raise their children to respect others and treat everyone equally need to teach these truths at an early age. Children are intuitively curious about everything, including people. You need to start embedding your family values in your child before they start learning about prejudice from others.
In 1 Corinthians 15:39 (NIV) it says, "All flesh is not the same: Men have one kind of flesh, animals have another, birds another and fish another. As you can see, God created man equal. He purposely put all men in one category with the same flesh, and then separates us out from animals, birds, and fish. He does not say white people have one kind of flesh and African people another kind of flesh. All men have the same flesh in God's eyes. It is very important that our kids get this nugget of wisdom in them early, so as to avoid confusion and conflict later in their life.
Prejudice does not stop at just color of skin, but also with religion, gender, and physical abilities, among others. The underlying cause for not being prejudice is that all people are equal in God's eyes, and therefore all people deserve to be treated the same, with love and respect.
Here are some tips to help you teach your kids not to be prejudice:
Be an example. Children learn so much from the adults around them, including how they react to situations, who they put down or build up in conversation, and how they treat others. If you want your children to learn not to be prejudice, you must practice this yourself. It should be a family value that is not compromised situation-by-situation. Consistency on your part is probably the paramount way to teach your child not be prejudice.
Invite friends over. When your child has made friends with another child that is different than your family, encourage her to invite this friend over to play and have dinner. Interact with the friend, and your child will be comfortable knowing that you have accepted someone different. If the shoe were on the other foot, your child would be the different one, right? Wouldn't you want that family to treat your child kindly, too? Remember the Golden Rule, "Do to others as you want them to do to you." Luke 6:31 (NIV).
Literature. Encourage your child to read literature about a wide range of people and take time to answer questions that arise. Giving your child things to read will broaden her perception of the world and help her understand how people are different in some ways, but always the same in most ways.
Scripture. Give your child Scripture that points to verses about men being created equal. Seeing God's Word before her should help solidify the fact that God did indeed want us to treat all people with love and kindness.
Pray together. Take time when you pray with your child to intercede on her behalf for God to give her an unconditional love for others. When a parent prays for their child, it is a powerful message to the child that she is protected and loved.