Findings from extensive genetic research tell us that every person with light coloured eyes has a common ancestor who lived in the Black Sea region around 10,000 years ago. As this person's offspring gradually drifted away from its point of origin and migrated north to colder climates, blue eyes gradually became a dominant feature in Northern Europe.
Looking at my own family, I can see the pattern. Two of my sisters have blond hair and blue eyes, so does my father and his father before him. My great-grandmother had blue eyes and my grandmother had grey. One of my sisters has four children and two of them are blond haired with blue eyes. Very Estonian!
My sister Sarah and her son Jakob are both blue eyed.