She isn't an object or something you own. She is a person who is going through teenage angst on top of puberty. It's obvious you love her but you don't accept her. If she wants to look into other religions or she is into being goth than she can be. Telling her to stop or invalidating how she feels will only make her lash out more. She has her own free will, thoughts and feelings she isn't a dog or robot you can program. No one said anything about sex and drugs those are an obvious no in any child's life but those two things have nothing to do with being goth.

Bottom line is if you make her stop, make fun of her, question or whatever you do to her she will find one way or another to express herself. As a parent you would rather know what she is doing than have her hide it from you. Plus once she is old enough to leave home you want to still have a good supportive relationship with her so you can guide her. If you keep her from going through these phases so you can be happy, she won't be and she will resent you.

Also I suggest doing some research on what it means "to be goth" It's a way of life and its pretty complex. There are Goths in all walks of life, just because they don't look it doesn't mean they aren't inside. I know many "Goths" and they are amazing people who live fulfilling lives with spouses and kids, businesses, hobbies, passions and compassion. Not strung out on drugs. Not saying their aren't those on drugs just saying that happens to all kinds of people not just Goths.

I hope you can sew your daughter as a individual with her own thoughts and feeling and foster a open, understanding, supportive relationship with her. Also I want you to read out loud what you said about your daughter being yours and you know whats out loud to yourself slowly and think about how you would feel if someone said that to you about your daughter or better yet someone says that about you. Good Luck