I also have a red-green color blindness. I am from the khandaan of pure purohit and they still are. But I am not as white. One more point, where do you find out that Brahmans ever got mixed with Mongols? It was heard that they mixed with the Dravidians that's you they turned a bit dark skinned as they are in South India. In fact, Chhetries mixed with Mongols and that's why you find same surnames in both casts. Like Rana, Rana Magar, Thapa, Thapa Magar, Budhathoki, Budhathoki Magar etc. My cousin's nick name is कुइरे coz he looks like white and has absolutely brown eyes. I wish I could show you the picture but in my lastnames, there are many of them who look like कुइरे and have brown and green eyes. It is true that most nepalese don't know what brahmans mean. They collectively term all the pahadia hindus as bauns.