Replying to Help me convince my parents to let me grow out my hair

My bangs are down to the tip of my nose if i lay my hair down straight. So it's not even long yet and they are already on my back about cutting it. They don't like long hair at all. If it were up to me I would have a man bun by now. I am a junior in highschool. Their only real argument is long hair looks bad. I say it's my hair I can do what I want, my brother had long hair, but he is in college so my parents don't really have a say. Help me out here guys