Biologically, redheads are really rare—the trait only occurs in 1-2 percent of the worldwide population, though it's far more common in Ireland, where 10 percent of the population is a natural ginger and nearly half of all Irish people carry the recessive gene for red hair. In Hollywood, though, sometimes it seems like every single actress up for an Oscar has red hair. How could this possibly be?

Dude. Clairol. 

Let's see if you can figure out which celebrities are natural redheads and which ones just have a good hairdresser.