Just as no two snowflakes are identical, no two humans are either. A new born child cannot be rational. It can't tell left from right, up from down, right from wrong. The way our eyes are wired it takes several weeks for the infant to make sense of the photons touching the rods and cones at the back of the eyeballs to figure out that "mom'" is not upside down.

You hold a set of beliefs based on family, friends, church, teachers and experiences. The older the belief structure the more firmly we tend to hold onto it. The way we think of things is sometimes called our "world view."

Now imagine several changes:

1, You were born one or more year(s) earlier or one or more year(s) later than your birth year: you would be in a different class in school with different teachers. The world would be different!
2. You were born ten or fifteen miles from where you were born: different town, different schools, different things to do.
3. You were born a thousand miles from where you were born: different part of the USA with its different regionalism with its quaint likes and dislikes.
4. You were born to a family of a different faith.
5. You were born in a different country: really different likes and dislikes and language.
6. You were born in any of these scenarios with a disadvantage: something other people view as "different."

It doesn't take much to have a completely different world view. Translate this into who becomes "us" and who becomes "them." After the sixth grade few people change their world view: their dogma, superstitions, their prejudices, their likes, their dislikes, their loyalties, their hatreds.

This is because after that point hardly anyone questions what they believe and why. They accept inputs what "agrees" with their world view, and reject those which don't.

Do your self a favor: question everything you consider 'True." Question these beliefs based not on the principle source of the belief, but a coherent study of them. Do witches really cast spells? Is 13 really an unlucky number? Does the position of Mars really affect you?

No two people have the same world view. You can see how many ways there are to look at the same issue: no wonder no one agrees with you.