Why do people get upset when they find a black hair on their kids

My name is Briana and this is my issue. I've seen these Instagram posts go around, specifically moms saying when their biracial kids are 3 or 4 and get their first silk press for school pictures or a ballet recital, and they find a black hair in their head. To me this is just normal genetics from parents passing down traits from their genes and since I'm black this just makes sense. I guess what I don't get is why it's a big deal for these moms.