40 something

YUP, We’re all getting older… one day at a time.
But as the youngest sibling - I have the distinct honor of having grey hair where my older brothers show no signs. According to Cecil, hair turning grey is just genetic odds. It was slipped into my DNA cocktail long ago. My question is… Why is my hair darker (like days of old) ONLY when wet?

My day starts with a shower and grooming. A spritz of hair gel, a quick brushing, No problem - I’m off with wet brown hair. Shortly after I have retreated from the bathroom mirror, my hair apparently dries and settles to a much lighter (OK, greyer) shade.

I failed Science class but I am braced for some refractive light theory.
Does anybody know??