Plucking out one gray hair will not affect the melanocytes in the other hair follicles, so other hairs will not turn gray as a result. In most cases, gray hair will occur as a result of age or a medical condition.
Here are a few more interesting facts: Your “gray” hair is actually transparent, but appears gray due to the dead cells that make up the strand. Also, smokers are four times (ouch!?!) more likely to have gray hair and premature hair loss — another good reason to quit.