Because humans are born with their foot in their mouth and their head up their ***. A selective few grow out of that.
Because people confuse "different" with "better".
Immaturity. All outdated values accepted in the past will be radically replaced with new values conceived by the mature human race.
Because some people are ********.
It's human nature to be judgemental esspecially when it is passed down through generations. Children are'nt born hateing it's what we teach them. To stop the hate we have to start with the new generations.
It's basic human nature, although much more prominent where people are undereducated.
because of the aliens