One aspect of defining which - you are, is your hair colour. This does not include what colours you've died it, or if it's turning gray. Your original haircolour, and only that colour is what chooses which - you are. The only exception is if your hair changes colour over time naturally(not including turning gray). For example, some people are born with white-blonde hair, and it faded brownish as they age. Also, some people have naturally streaks or highlights in their hair. If this is the case, just go by the base colour, or the colour most prominent or visible. There may not be an examply replica of your haircolour to choose from, so choose the one closest to it.
