Why are people born in the 90s racist? Because racist people keep breeding and pass on the ignorance.
It's quite true. My gramps was from Texas and really at an age where I "accepted" most of his rants due to his age and location when growing up. To be fair, he made many turn-arounds in thoughts and opinions, and that is actually saying a lot... that even decades stuck in his ways, he could still find it in him to change some opinions.
They are afraid.
Because that's the environment they grew up in (people of both sexes). I'm not justifying it in any way, but that's why. It's been engraved in the way they perceive society/the world, and it's a way of thinking that will hopefully dissipate as we evolve as a global society.
It's not really their fault in a way. These attitudes were deeply engrained in them from children. Old people can be really racist. My great grandmother used to carry around a rag to wipe things in case a black person had touched it. Hard to blame my grandmother for being racist too (she's no where near as bad, but just a few comments here and there).