I was a rebel, not against my mother, but against a world that preaches but doesn't practise. I was quite violent - one teacher said I had an avenging angel complex - and much enjoyed sex. I loved school and learning but wanted to argue the point about everything.
I'd worry more about the young people who don't rebel, the sad conformists that want to leave the world as they found it, but with more money in their pocket. But there are so many dangers now, drugs, unplanned pregnancy - I was protected - and crime. You know you will get the opposite effect if you go at your sister like a bull at a gate, but you may also get up her nose if you come the old "I'm your friend, I love you, lets' talk about this" stuff. Like politics, living with some adolescents is the art of the possible. Let the small things go, get her protected against pregnancy and concentrate on what you can reasonably do to help. It will be a longish task - you can't get instant result. Whatever you do, don't fall out with her - you''re her last resource it seems.