Eye cancer; Trauma to the eye (e.g. in an accident) If your child is born with heterochromia, it's unlikely that they have any other eye or health problems - but it's still a good idea to see your GP.

According to Healthline, 45% of Americans have brown eyes, 27% have blue eyes, 18% have hazel eyes and 9% have green eyes. That means there are tens of millions of blue-eyed people in the U.S. alone.