How can I convince my parents to let me watch Dexter?

I'm 16. The other day, I saw a trailer and some edits for the new Dexter prequel (original sin, I believe it's called). It looked interesting, so I wanted to try and watch the original show, so I watched the first episode. But when my mom found out that I did she was very upset and wanted me to stop watching immediately, probably because she thinks I'm gonna become a serial killer if I do... But, to be honest, I'm kind of hooked after the first episode. Any ideas for what I can do?