Gray and green eye colors are the rarest in the U.S., although extremely rare red color can occur with albinism. Eye color is determined by the amount of melanin in the iris, with more melanin making ...

When it comes to celebrities, people tend to focus on their physical traits, especially the characteristics that make them unique. Some have rare eye features.

Forbes contributors publish independent expert analyses and insights. I write about biodiversity and the hidden quirks of the natural world. For most of human history, green eyes didn’t exist.