Colour blindness is one of the oldest established genetic diseases (first described by John Dalton in the late18th Century).
The most common forms are linked to genes of the chromosome, which is why the trait is common in males – with only one X chromosome, if they inherit a faulty gene from their mum then they don’t have another copy to compensate.
I got my faulty X from my mum, and so have difficulty distinguishing shades of brown and green, but otherwise my vision is normal.
There are other genes that cause colour blindness when mutated, but these changes are much less common than the one on the X chromosome. In fact X-linked colour blindness is so common that some scientists have suggested that it might have an advantage – particularly by enabling people to see through the camoflage patterns if predators or prey….