Melanin Determines Eye Color

Your eye color is only unique to you, no one else has it.  Eye color may change in the first 3 years of life, but there is no way to change it in adulthood.  You can disguise your eye color by wearing colored contact lenses, but its not recommended.  The more melanin pigment in your eyes, the darker they will appear.  Someone with green eyes has less melanin than someone with brown eyes.  

For more information, this optometrist in Redondo Beach has posted an explanation on how eye color is determined.

http://advancedeyecarecenter.net/blog/industry-news/An_Optometris_in_Redondo%20Beach.php

http://advancedeyecarecenter.net/south-bay-area/redondo-beach/