All who have siblings are familiar with the torment they bring (they can also be really nice but anyways...my angsty teen self is on a role here). This (rantish) post is mainly about how they can react to your movement to the dark side. (Edit: Reading back, I spot quite a few 'I's in the first paragraph, so sorry about that :P)
I have two siblings, an older sister (14) and a younger brother (11). My brother is wonderfully unsexist, not too obsessed with popularity and tries not to judge on what someone looks like. My sister isn't as bad as most other girls in her year, but she's a bit of a fashionita (that's not even a proper word and I still think I spelt it wrong...does that even make sense?, a bit of a slut shamer, and dislikes people who are 'different in a bad way'. What do they have in common? They both call me 'emo' a lot, and tell me to 'please stop dressing so freakily, because it's embarrassing them'. God, siblings are ANNOYING!!!
This applies to all people, not just family. We are Goths (not emos, Goths) for a reason. We are't going to stop dressing in a way that makes us feel more confident because you tell us to. We aren't going to trade our creepy music for your pop. We aren't going to stop identifying with a (rather wonderful, in my opinion) subculture because 'it's embarrassing you'. Tough luck.
Siblings can also be really great of course, as can friends :D