The reason why some people with dark ancestry remain dark, even when mixed with genes from pink people (have you ever seen a living person who is really white?) is that some genes are dominant. Brown eyes are generally dominant over other colors and those with one brown gene and one other colored gene will thus have brown eyes. This is more complex than this, of course. My mother had brown eyes and olive skin and my father had pink skin and pale blue eyes. All three of us children had pink skin and an eye color half way between our parents. In our case neither of the color genes was entirely dominant. It happens.