O thanks for bringing up this subject!
Suffer an array of minor anomalies, like a little more quiet, a little more inquisitive, a little more sensitive, not laughing at the all the same stuff, not frightened by all the same things, have a slightly different manner of speech, a slightly different culture, be a little skinnier or more plump, a little more petite or more robust, etc - and somewhere there is a tipping point, fear kicks in and you are quietly and subtly ostracized...
Just one or two anomalies gives character, makes you even more likable for not being perfect, but there is a cutoff point somewhere - has anyone ever researched that?
Maybe "poly-factorial discrimination" could be a fitting term?
Lies the cure, if any, in strengthening the victims, or in educating the offenders? - discrimination is as natural as breathing and cannot even be bred out of existence!