Getting grey hair is part of the natural process of ageing and is also down to genetics.
Hair does not grow grey in a uniform pattern.
It is quite normal to have a little more grey on one area of the head that the other.
If you are worried about your grey hair, you can buy hair colourants.
Gray hair and balding are both genetic. I haven't seen any articles yet that say why your hair would gray only on one side. So far I have only seen that it is genetic regardless of the pattern.
mkh9
Premature "gray" is not a medical condition. Just genetics. But if you are really concerned about it, there are vitamins one can take to make the hair dark again. They are pretty expensive - and I don't remember what they are, but if you are interested, I'll try to find out for you.