"dps, so if blacks could change the color of their skin, it would be ok to discriminate against blacks?"
Hmm interesting question. If race and ethnicity were choices we made rather than accidents of birth I'd have to say yes, discriminating based on those would be ok. Whenever we make a choice we have to accept the consequences of that choice. If I get a tattoo that covers my whole arm I accept that I can't where short sleeves to the office. If I dress in a style associated with criminals I accept that people are going to be watching me more closely. If I have the option to change my race/ethnicity and don't I'm still making a choice (the choice not to act) and again have to accept the consequences.
I do however feel a small amount of sympathy for those who have choices forced upon them (people who dress like gangbangers cause they can't afford clothes that fit properly for example). However this sympathy does not extend very far.
There are 10 kinds of people in this world, those who understand binary and those who don't.