It's sometimes called being "colour blind", although total colour blindness (an inability to see any colour) is very rare. Colour vision deficiency is usually passed on to a child by their parents (inherited) and is present from birth, although sometimes it can develop later in life.

What is the chance that A will be color blind?

Each daughter has a 50% chance of being a carrier and each son has a 50% chance of being color blind.

What is it to be colour blind?

Having color blindness means you can't see certain colors the way most people do — or you may not see color at all. Learn the basics about color blindness. Different types of color blindness cause problems seeing different colors.