All Caucasians Have Blue Eyes, All of the Other Races have Brown Eyes...NO Exceptions!
Now, all White People have Blue Eyes if they are Caucasian. And if they are White-Caucasian all 4 of their Grandparents will also have blue eyes. Hence Blue mixed with Blue-can only make blue. And this doesn't mean that all White-Caucasian people with blue eyes are White or Caucasian, it just means no other races are showing by their eye color. When Caucasians begin to mix with other races eye color is always the first to go, then facial features, hair and skin tone. Brown hair color is also a non attribute of the Caucasian race.
Anyone with Green eyes is Multi-Racial and part Caucasian. NO Exceptions! Hence you need blue to make green. And the Caucasian genealogy will be close or they wouldn't be Green and would be Brown.
Same goes for the Native American race, all Native Americans have Brown eyes. As did all 4 of their Grandparents, hence brown mixed with Brown can only make Brown. Same goes for all other Races, Asian, African, Arabian, will all have Brown eyes as did all 4 of their Grandparents. Hence Brown mixed with Brown can only make Brown. Now this doesn't mean that all Black people with Brown eyes are African, lets keep in mind Brown is the dominant gene. (Most Black People in North America are Not African and are Multi-Racial - African, Caucasian and Native American Ancestry)
Now, if you have a person who appears to be White-Caucasian, who has Green or Hazel or Brown eyes, That's because they are not White-Caucasian and are Multi-Racial with a Mixed Ancestry-Caucasian-and what ever other race or races is making their eyes Brown. or Green. Or Hazel. Hence it takes Brown and Blue to make green or hazel.
All people who have Hazel or Green eyes are Multi-Racial. No Exceptions! Neither Hazel nor Green eyes are indicative of any race and are eye colors derived from Race-Mixing.
Very Few White-Caucasians have Gray eyes, this is from their strong Caucasian Genetics, which Caucasians derived from the altitude of living high up in the Caucus Mountains which turned their Blue eyes Gray and Some Asians living in higher altitudes (however very few and very rare) will develop gray eyes also from living in these altitudes.
So usually you can use a geographical reference based off of statistics, like for instance if a person who appears to be Caucasian in say Georgia and has brown eyes or Green eyes or Hazel eyes, means they are not white and are Multi-Racial and it will be most likely because he or she is of part Native American mixed with Caucasian Ancestry.
Now a person who appears to be Caucasian with Brown eyes or Green eyes in Italy, most likely isn't going to be mixed with The Native American Race, since No Native Americans are indigenous to this geographical region. Most Italians are Multi-Racial of a Caucasian, Arabian and or African mixed ancestry which makes up the Latin Race. And a person who appears white, say in Spain or Portugal with brown eyes (since so few have strong enough Caucasian genes to produce Blue eyes) will not be White-Caucasian and are Multi-Racial with a mixed Caucasian, African and Arab Ancestry-from which also comes the Latin Race. Then later The Latin Race adding Native American Ancestry to their Genealogy by way of the America's, Hence Latino, Who are all also Multi-Racial.
So If you have Brown eyes, or Green eyes or Hazel eyes, being White-Caucasian would be Impossible. An Impossible event with a 0% statistical probability of being the truth. And on the flip side to this, if you have Green eyes or Hazel eyes (like myself) you are Multi-Racial-100% statistical probability of being the truth. After all Jesus was Multi-Racial
Race was invented by the European to divide other peoples, with Oppression intended. Mitakuye Oyasin! means "We are all one" or "We are all related", also translated in Jamaica as "One Love" or "Out of many we are ONE" and we are, everyone is of the Human Race, and people of all colors all have the exact same ancestors.
So, In Conclusion-Everyone is Multi-Racial. Mitakuye Oyasin!
1. Multi-Racial -as of or pertaining to more than one race.