I think there was a girl who discovered some telekinetic powers in some kind of car accident. An old neighbor lady turned out to be her helper or guardian and told her she was an alien. The girl's brother (maybe twin) is disappointed he is not. The girl had faked some blood tests in school because she kind of knew she was different, maybe because of the color of her blood? I read this as a kid, probably around 1986, translated into Danish. Sadly, I can't really remember it.