Sometimes stupid just comes out

I was at the grocery store this weekend with the kids. I was shopping in the later part of the evening so I was not as familiar with some of the night shift workers. I got in line to pay for my stuff and the cashier was staring at my kids. She then asks me if the girl was my daughter (meaning Briahnna). I told her yes and that all 3 of the kids were mine. She then goes on to say (in front of my kids and other people around) "Oh, I did not think she was your child since her skin is dark and her hair is different". All of our mouths were on the floor and in my head I cussed somethin' nasty. Of course I am a lady and I told her that she was indeed my daughter. The lady then feels like an ass and makes some other comment about hair straightening and I just took my receipt and left. I felt so bad for Brie since she looked like she was confused. How could someone say something so ignorant and stupid and make a kid feel bad? I told the girls that I was really annoyed about what she said and they both told me they too were very annoyed. We spoke about it for a few minutes and had to chalk it up to ignorance and the fact that just because you are blood related to someone does not mean you are supposed to look like them. I think it took me 24 hours to get over it. I just know that people should never assume anything when they see that kids of the same family do not look alike. I have seen families with kids of multiple races and it does not phase me. I just know that I reassured all my children that they are all beautiful and uniquely themselves. There will never be anyone else like them in the world.