6. Gray Eyes
Most people born with red hair have either brown, green, or hazel eyes. A combination of blue eyes and red hair is even rarer, as both traits require both parents to have the gene. And blue eyes are already quite rare in and of themselves. Only about 8% to 17% of the human population has blue eyes.
However, gray eyes are even rarer. According to the World Atlas, less than 1% of the world’s population has this incredibly rare body feature. This occurs due to a low level of pigment (melanin) in the front layer of the iris.
Meeting someone with gray eyes is pretty unlikely, but your best bet is in Northern and Eastern Europe, where green eyes are also more common.