How do you deal with people when they say mean things to my siamese?

how do people respond to questions like "why is her face black??" LIKE WHO ASKS THESE QUESTIONS

How do I even respond to a question like that it bothers me so much (I tried explaining them its a natural thing which also I dont have to fricking explain that ik but I was trying to explain thinking it came from a place of curiosity but no they did not care about the reasoning they just wanted to say it out loud that too infront of a group of people). I brought my cat to introduce to my friends Any advice is appreciated.