There is always a catalyst for racism. Discrimination is present in all of us to one degree or another, whether it be because of someone's skin colour, gender, sexuality, the football team they support or even some supposed grievance from years ago.
My mother-in-law forgave the Japanese for turning one of her brothers from a 6' tall 14 stone Sergeant drill instructor into a 5'8" 6 stone shambling wreck who died not long after the War aged 35. My Grandmother forgave the Germans for killing one of her brothers who was in Bomb Disposal with a booby-trapped 1 ton aerial land mine. There was nothing left to bury. Yet there are still Scots who genuinely have the best day of the year if England lose at football. (Linwood no more, Bathgate no more) There are Irish who still hate us for the centuries of occupying their country yet the Indians don't bear us the same malice.
Some of us on here can still remember how racial tensions went up a notch or two during the last recession and in the '60s it was fear of job losses ( as well as ignorance) that led to the Dockworkers' unions teaming up with Enoch Powell (Rivers of blood) to protest against immigration.
I've lost count of the number of people, who, after spending time with the people they thought they hated, actually turned round and said: "Actually they're not as bad as I thought." (Backhanded acceptance that their predjudice wasn't as justified as they thought.)
Homophobes often think that way out of fear. Fear that Gays are predatory sex fiends who are trying to have sex with any and every male they can find and fear they might actually be gay themselves.
My first girlfriend was a Sikh (it was her dad that broke us up) the 2 mates I spend the most time with are a West Indian and a Hindu and I am part French, Italian, Irish, English and now, it would seem, part Jewish.