If your mother had blue/green eyes and your father had brown eyes ... ?!
Question:
If your mother had blue/green eyes and your father had brown eyes ... ?
What would the possibility of the child having grey eyes, be ?
What colour eyes do you think the child would have ?
Answers:
"Worried person" is basically right, but he should have told you that an allele is one part of a gene "pair" that determines eye color.
The possibility of the child having grey eyes is extremely low-like almost 0 (that's what I would answer on a test in school) But it IS possible, because if the father is a Tt and the mother is a tt, and we know that both the mother's parents had to have at least one "recessive" gene for blue or green. If you go back further on the family tree, you may run into an ancestor that also had tt (two recessive genes), and an eye color more closely resembling grey/blue. And maybe that recessive individual had a parent whose eyes were more grey than blue (because of the diversity of the pigment in an individuals eye whenever they have two recessive alleles).
Worried Persons math is correct and his prediction is "most likely". All I'm saying is that it is not impossible for a "grey" eye color to have appeared in the ancestral tree going back generations that may suddenly reappear in the present generation.
That's why you see so many "shades" of blue eye color and variations in green eye color.