Oh, and if you want to talk about frustration, try this one. My Grandmother, born in 1876, decided one summer in the 1950s that I could be trained to see colors. She had me sitting in her living room by the hour, vainly trying to identify and match skeins of embroidery thread. God, but that was frustrating! My Mother, her daughter, explained to her that the problem was a genetic thing and that I truly could not see the colors.
AFAIK, it is genetic. It is a gene linked to the "X" chromosome, but it is a recessive genetic factor, so that it never shows up in females unless they have it on both sides. It must run pretty strong in my Mom's family for my brother and I are both color deficient but neirher of my sisters are.