Ladies and gentlemen, our first gray hair is a rite of passage, a reminder that we're getting older, wiser, and that we are blessed to be a vibrant human being. Like laugh lines, gray hairs are a totem of a life well-lived.Here's everything you ever wanted to know about being a silver fox or dyeing your salt-and-pepper strands.What causes gray hair?Hair graying is an irreversible reality of life a …