Quit Ticking Me Off

As most people know, we have three children. The oldest two definitely look like brother and sister, but the third one doesn't look anything like the other two. The older two have dark brown eyes and brown hair. Sierra has blue eyes and curly, blond hair. Very often I'll get the comment , "I can tell who the other two look like, but I can't tell who she looks like." I've even had a couple of comments like, "Where did she come from?" and "She must be the milkman's daughter." Sometimes that makes me so mad, I feel like getting a paternity test just so I can pull out a paper and say, "See! She belongs to both of us!" People just don't realize that I had very blond hair when I was little, and curly hair runs in my family. There are also blue eyes on both sides of the family. Sierra just happened to get all the weaker genes. Thank you very much.