As I said, it is not always well understood by the medical community. I personally went through a lot of physicians before I got some hard answers. The gene that causes colour blindness is hereditary through the female. Daughters carry the gene, sons suffer from it. The light receptors on the back of your eye consist of rods and cones.
Cones are the receptors for bright light and colour.
Rods are the receptors for geryscale and low level light. Cones are centred in the middle of your eye, directly behind your eye lens, while rods tend more aorund the outside. If you use averted vision during visual observing, you are actually trying to use your rods over your cones. In colour blindness, it may be that a person has more rods than cones, it it may be that the cones are not fully functional - depends on the individual and the specific form of colour blindness. There are a couple of ways.