Why do i have green eyes?

I wanted to know why i have green eyes, my mom has blue eyes and my father has brown eyes, i thought there was a recessive allele for blue and dominant for brown an when the dominant allele appeared the eyes would be brown, one of my sisters also has green eyes and her father is different from mine but he also has brown eyes, but my other sister [from the same father as my other sister] has brown eyes, so is green a color between brown and blue?