Eyes

[Sally]

Why do some people have different coloured eyes i.e. one blue one green, one of my eyes is half blue half brown why?

[Nellie2]

Now this was a question I was interested to find the answer to. The colour of our eyes is determined by the amount of "melanin" in the eye. A lot of melanin produces darker eyes (eg brown). Very little melanin produces light blue. The other colours are all somewhere in between. Two different coloured eyes is a condition known as "heterochromia" and it occurs naturally in about 1% of the population. And the most common combination of two colours??....... Blue and brown (just like you). An eye injury can cause heterochromia but it is most commonly genetic. One theory is that a mutation occurs in the eye melanin gene at the time a cell is splitting. (By my thinking this would account for two eyes of different colours, but not one eye of two colours like yours). However..... many many people have more than one colour in their eyes (if you look closely) but it is generally in a speckled pattern. Now perhaps someone can answer this. My eyes change colour and can be golden brown, grey-green, green, or blue-green. Why is this so?