Color Blind isn't the best term and we should use color deficiency. The reason is when people hear Color blindness they think these people who can't see any colors. If someone can't see any colors and only sees in white, greys, and black then they are Achromatopsia which is extremely rare 1/30,000. Most people that are color deficient are normally red/green deficient. Most of the people who are color deficient are Deuteranomaly see photo below for an example of their vision.
Now you probably wondering how most people get red-green color deficiency. The simple answer is they are normally born with it. Both Deutans and Protans (both are red-green color deficient) are normally passed from mother to son, very rarely from both parents to daughter. The reason why is that Color deficiency is an X-linked recessive gene. Reminder XX genes are female and XY are male. When a male is color-deficient and has a daughter the daughter is a carrier of the color-deficient gene. The daughter is normally not color-deficient unless the mother of the daughter was also a carrier of the color-defiant gene or color-deficient herself. Even when the father is color deficient and the mother is a carrier of the color deficient gene 100% of all daughters will be the carrier of the color deficient gene and only 50% of males, and 50% of the females will be color deficient. If the husband is color deficient and the wife is not a carrier or color deficient then no males will be color deficient and there is a 100% chance the daughters will be carriers of the color deficient gene (they won't be color deficient themselves). If the Husband is not color deficient and the wife is a carrier of the color deficient gene then males will be color deficient 50% of the time and females will have a 50% chance they will be color deficient carriers. I'm going to talk about Deuteranomaly, and Protanomaly is vs Duteranopia, and Protanopia. Deuteranomaly is when your green cones don't activate at the correct wavelength of light as a non-color deficient person and the green cone is shifted towards the red spectrum of light making your red and green cones see very similar wavelengths of light. Protanomaly its red cones shifted toward the green spectrum of light. For the -Opia the red or green cone is missing. Tritan is normally due to disease (blue-yellow color deficiency). Achromatopsia is due to a mutation in the genes. FYI we do screening color deficiency tests here at Eyecare Redefined in Katy/Fulscher on every new patient for their routine eye exam.
