I'm a teenager with gray hair? I don't think it's a big deal, but...?

I have gray hair and I'm a teenager. 14,actually. I don't actually mind having gray hair because I'm grateful that I have hair. I just think it's hereditary thing from my mother and that's what I tell people, but they still make fun of me. I think my gray hair is caused by stress or a genetic disposition, but I just think it's hereditary since my mother has it. I'm tired of people making fun of me and acting all surprised when I have gray hair. I find it ridiculous and absurd when people my age find out that I have gray hair and make fun of me for it and act like it's the apocalypse because I have them. I can't help but be bothered by this and I have dyed my hair plenty of times before (just black, though.) to cover up the gray, but it never lasts more than a month or more. How to deal with people who make fun of me because I have gray hair? I really don't think it means you're old, but a lot of people think it does.