Błędnie: Has your brother always been so discriminating? He seems to hate most people who are different than majority. Poprawnie: Has your brother always been so intolerant? He seems to hate most people who are different than majority.
"Discriminating" oznacza 'wybredny'(o guście), 'wyrobiony', 'wnikliwy'. 'Nietolerancyjny' (skłonny do dyskryminowania innych) to "intolerant".