I have like 3 but ever since I got my highlights heavily layered, I can't seem to distinguish where they are nor can I tell them apart from some of the light blonde! I'm 18 but my 12 year old cousin is nearly 25% gray. NO JOKE! She had them since she was born and it they kept appearing! My really really old wrinkly grandma says its bcuz her father was old. I think her father was 40 something when he had her. gross...